Like Fallout 3, you can use this trading exploit to earn essentially infinite amounts of caps, items, repairs and ammunition. Here's how:
1. Find any shop-based trader and sell him any stuff in your inventory that you don't need and complete the transaction. This will boost the amount of money he has.
2. Find something in your inventory that you have two of or something that you and the shop keeper both have. Sell an item or two to the trader so he has two of them.
3. Check that the two identical items are of different values once they are in the trader's inventory. The bigger the difference in value, the better.
4. Now buy the cheaper of the two identical items and complete the transaction, but do not leave the trade session. Look for the item in your inventory. The item should have gone up in value dramatically and should be 100% repaired, even though when you sold the item initially it wasn't! If it isn't 100% repaired for whatever reason, sell the item back to him anyway and repeat steps 3-4, trying a different item if necessary.
5. Now you will be able to sell the same item for a high price and buy it back at a low price until you have drained his money completely. If you want, you can hold onto the item as it will be fully repaired -- simply keep it on the final round which will leave him with a small amount of money. Either sell the item back to him again once he is out of money, or if you are keeping it, sell him something else of high value and he will owe you that amount. The transaction price will go dim and remain at whatever amount of money he has left.
6. Search through the trader's inventory and find stuff you need. Stimpaks, ammo, miscellaneous item, weapons and armor are all fair game. Eventually, the transaction price will light up again and you may owe him a few caps depending on how much of his stuff you added to the deal. Complete the transaction.
7. If you wait three days he will have new stock and around 650 caps. The longer you wait, the more robust his inventory will become and the more caps he'll have for you to take when you're ready to do this all over again.
Note: Be sure to save while using this method since the game is prone to crashing during the transaction.
Each weapon type in Fallout 3 has a unique weapon with special capabilities. Here is a list of where you can find these unique weapons.
Abilene Kid LE BB Gun: The Abilene Kid LE BB gun is a unique BB gun. It can be found in Fields Shack on the shelf to the far left corner of the house. If you have the Wild Wasteland trait from the beginning of the game on, it will be located in Jimmy's Well, which is just outside of Fields Shack. If you have Rex the cyber dog, and you talk to him with the Wild Wasteland Trait, he might start howling and eventually he will mark Jimmy's Well on the map for you. You get a variety of guesses to figure out what's wrong, but the correct one is that someone fell down a well, which is a reference to Lassie. Fields Shack is located between Nellis Airforce Base and New Vegas Medical clinic, if your having difficulty, it's North East from the clinic, and South west of the airforce base. It's on the road to and from the Airforce base, you should see a guy named George, warning you about the Boomers and their artillery guns.
AER14 Prototype: This laser rifle is located in Vault 22. This vault can be found between Westside and Jacobstown or by doing the side quest There Stands the Grass for the scientist at Camp McCarren. Once inside, you'll find the rifle on the fifth level-pest control, behind a (very easy) locked door leading into a blocked off area of the fourth level. Look on the ground next to a skeleton and there it is.
Alien Blaster: Find the crashed alien ship near top right hand corner of map. The ship is on top of the cliffs. Below are 3 aliens. Kill the captain for the blaster and ammo -- like Fallout 3 it's one of the best guns in the game.
All-American: All American is a unique Marksman Carbine. You can find it at the armory in Vault 34. First, find the passwords from the drowned techies underwater -- it helps if you have the rebreather. Find the terminal that holds one of the passwords, that will unlock a door. That leads to another room with another drowned techie. Take that password to security sector A and there is another terminal that will control the pump to drain the water. This will give you access to another room that you couldn't reach before. Using the new found password, you will unlock the Overseer door and with that terminal. You unlock the armory door that holds All American and a crap ton of other loot. Beware of ALOT of feral ghouls. All American is found on a turned over table directly to your right point of view once you enter the room. Vault 34 is INCREDIBLY confusing.
Annabelle: Annabelle is a unique missile launcher carried by a super mutant sniper, on Black Rock Mountain, on Black Rock Summit, somewhere near Goodsprings and Jacobson Town. the mutant is on what looks to be a electrical tower or a radio tower of some sort. He's carrying Annabelle -- you can't miss him, he'll be the one shooting you on top of a radio tower. The place is SWARMING with nightkin and super mutant masters mostly and the place is HEAVILY irradiated, get armor and pop some Rad-X, this won't be easy.
Big Boomer: Big Boomer is a unique sawed-off shotgun carried by Old Lady Gibson in Gibson Scrap Yard, North of Novac. You must kill her -- preferably silently and undetected due to the amount of dogs with her. DO NOT kill her until you finish the "ED-E my Love" and "Come Fly with Me" quests, otherwise you will fail the quests.
Chance's Knife: Chances Knife is a unique combat knife located in Chance's Grave, which is located at the tribal village. The tribal Village is located north west of Goodsprings Cemetery and North and little west of Goodsprings itself. The place is pretty obscure since it's in a very mountainous region of the map. The village is dangerous in a sense, since they are usually some Cazadors and a few Fiends. Bring a good weapon just in case. You need a shovel to dig the grave, and the grave is pretty obscure too -- it's on a hidden hill, near the village.
Chopper: The Chopper is a unique meat cleaver found on the stove of Wolfhorn Ranch. Wolfhorn Ranch is located South East of the Prospectors Den, which is South East of Primm, and the ranch is also fairly close to Nipton, North East of Nipton where the road turns right and splits into a bunch of roads.
Cram Opener: The Cram Opener is a unique bladed gauntlet carried by Little Buster who can be found in Camp McCarren, punching a punching bag. If you hunt Fiend bounties for the NCR, they will point you to Little Buster. You must kill him to get the Cram Opener. He will disappear eventually, so be quick.
CZ57 Avenger: Here is how to find the upgraded mini gun called the C257 Avenger. The easiest way to get to it is to find Ranger Station Bravo. If you've done the Return To Sender quest you've probably already found it. If not, it is six sections down from the top of the right side of the map, and between three and four to the left. Once you get there, travel east. You should discover a place called the Devil's Throat. It is highly radiated so have some Rad-X on hand as well as some Rad-Away. You can make pretty easy work of the Evolved Centaurs and the Centaurs there. Once you clear the area, this extremely fast mini gun is in the truck along with plenty of 5mm ammo for it.
Driver Nephi's Golf Driver: Nephi's Golf driver is a unique golf club, and is one of the "simpler" melee weapons to get. The golf club is located on Driver Nephi, who is a fiend, so either way, you will probably kill him. He is located around the area of Camp McCarren and New Vegas and is one of the three fiend bounties, so if you can't find him, activate the quest and it will point you in the right direction. You can activate the quest by talking to a guy located in Camp McCarren..
Euclid's C-Finder: Euclid's C-Finder is a unique weapon that uses the power of the sun to burn your enemies to ash. It can only be fired once per day -- and only outside -- because the lasers must recharge. To use this weapon, during the quest "That Lucky Old Sun," you must program the Helios One power station output to ARCHIMEDES. You can find it in freeside, near the east gate -- a boy named Max carries it. You can either buy it for 1000 Caps (or 20 Caps with a barter skill of 45), pickpocket, or take it from his bedside while he is sleeping. He goes to sleep around 9:30. He sleeps on the second floor of the building on the right after coming into Freeside from the East Gate.
Figaro: Figaro is a unique straight razor. You obtain this weapon by killing Sergio in the back of The Kings School of Impersonation. Try to be stealthy about it; everyone in that building has a gun. Sergio is the barber of the Kings.
Gobi Campaign Scout Rifle: The Gobi Campaign Scout Rifle is a unique sniper rifle found in the foot locker in the snipers nest overlooking Cottonwood Cove, a Legion hideout/base. You MUST have a Lockpick skill of 100 to open the footlocker.
Golden Gloves: If you want the Golden Gloves, look inside the Lucky 38 Casino in The Strip. Look in the Casino upstairs on the left side above the cashier station and look in the top shelf on the left side of the bar table. The Golden Gloves and the Boxing Times magazine will be right there.
Holy Hand Grenade: The Holy Hand Grenades are exactly what they sound like; grenades. You can find them in the most eastern church of Camp Searchlight, which is somewhere in the southern part of the map. There is a catch though: You MUST take the Wild Wasteland Trait at the Beginning of the game or the grenades will be replaced with a mini nuke for a Fat Man. The basement does contain some golden geckos and high radiation, so pop some Rad-x before heading down.
Knock Knock: Knock Knock is a unique fire axe that can be found in Camp Search Lights Fire Station. You need to have a key to the building so first go talk with prospector leader who is stationed at the church basement. Go fetch few radiation suits for him and then you can follow him to the police station and after that to the fire station. Kill this massive Queen radscorpion and grab a couple fire axes with you (can be used to repair the "Knock Knock"). Go to second floor and advance to the toilets. Open the second booth from the door and grab "Knock Knock."
La Longue Carabine: La Longue Carabine is a unique Cowboy Repeater carried by Corporal Sterling whom you must kill if you want to obtain it.
Liberator: The Liberator is a unique machete carried by Legion officer Dead Sea who is located in Nelson. If you're friendly towards the Legion, Nelson is located near the South east corner of the map, west of the Giant River that separates from the mainland. If you're friendly towards NCR, follow the quest for the NCR in Camp Forlorn Hope and talk to the commander inside the tent. Eventually he will send you and 3 other guys to retake Nelson. You will probably kill Dead Sea by the end of it. Search corpses until you find the Liberator -- it will be found on dead Sea.
Love and Hate: Love and Hate is a unique spiked knuckles. You can get it from Bonnie Springs (located north from Goodsprings cemetery). Kill Viper gang leader and loot her body.
Lucky: Lucky is a unique .357 revolver. It can be found at the Steve Bison place in Primm. It's behind the cash register in the gift shop, in a safe that's in the floor. The gift shop is the the most North Eastern part of the first floor. You must have a lockpick skill of 75 to open the lock.
Maria: This pistol is really easy to get. When you get to meet Caesar (Caesar's legion) all you need to do is complete a short guest from Caesar and after that you are given a chance to kill Benny. Kill Benny and then loot his corpse. You find this pistol "Maria", which by the way is the same pistol that Benny used to "kill" you when the game began.
Mercy: Mercy is a unique grenade machine gun is THE most difficult weapon to obtain in the game. First, it's in a rather obscure location, it's located in Dead Wind Cavern, and no one would think to look in there. Second, the place is friggin SWARMING with Deathclaw (normal, couple of alpha males and mother) and the absolute most powerful enemy in the game, "The Legendary DeathClaw". Make sure you KNOW what your doing, before entering, or it'll result in an untimely death. Mercy is located at the end of Dead Wind Cavern, next to a dead Brother of Steel member. It's in the same room as the Legendary Deathclaw. If you have Holy Frag Grenades, use them; these things will usually result in a one hit kill, WITH power armor.
The Mysterious Magnum: This unique weapon can obtained when you are doing a quest to bring in fresh talent for The Tops. One of the fresh talents is located east of the HELIOS Solar Power Plant near a roadside billboard next to the interstate road. If you can successfully recruit him and ask for a reward, he give you his dad's weapon, the Mysterious Magnum. Every time you draw out that weapon, you sound like you are the Mysterious Stranger, which we may now confirm the relationship.
Oh, Baby!: Oh Baby! is a Unique Super Sledge located in Charleston's Cave, located North East of Jacobson Town, just behind the gate, up the hills. Don't go to far, just around the town gate. The over powered weapon is on the ground next to the dead nightkin. The location is part of a quest, so activate it by talking to Doctor Henry. The place has some night stalkers in it, but they shouldn't give you much trouble. If you have the Wild Wasteland Trait on, there may be dead big horner corpses as well, it's easy to miss, but if you do, it could be under one of the big horner bodies, it helps to have Rex to help you spot it. If it is, just try to move the corpse, if that doesn't work, blow up the corpse using anything, guns, melee -- don't use explosives as that might send Oh, baby! flying somewhere and you can't find it.
Paladin Toaster: This is a special power fist that is found in Black Rock Cavern northwest of HELIOS One. You have to kill a few nightkin, and the toaster will be found on the corpse of a prospecter. This glove is pretty much an EMP punch that can kill at any unarmed skill level.
Pew Pew: Pew Pew is a insanely powerful laser pistol and can be found on the body of Allen Marks. To get to Allen Marks you must complete the quest, "The Legend of the Star" to do this, you must collect 50 Sunset Sarsaparilla blue star bottle caps and turn them in to Festus, the goofy broken cowboy guy directly left when you enter the Sunset Sarsaparilla headquarters. Pew Pew may be powerful, but there is a downside. This beast of a gun eats up 15 energy cells per shot. You may say, "I have a lot of cells, it won't be a problem." Yes there will be, you will be reloading often which makes firefights tough.
Pushy: Pushy is a unique Displacer Glove that can be found in the Ruby Hill Mine, which is on the trail near Jacobson Town. You will find Pushy on the body of a dead Jackal member Near a giant pool of water. The mine is crawling with swamplurks, but they aren't too tough.
Q-38 Matter Modulator: Head to the REPCONN Headquarters (North of REPCONN Facility and Novac). This unique Plasma Rifle (and item that Marvin the Martian always looked for in Looney Tunes) is found on the first floor. The easiest way to obtain this weapon is to make your way to the 3rd floor and find (beside the pile of rubble the B.O.S. patrol is under) the suitcase a skeleton is holding. Open it and remove the security key. Go to the second floor and find its corresponding door to enter a room with a hole in the floor to find the rifle in the corner in a strange container.
Ranger Sequoia: This is a super-powerful 45-70 revolver. It can be found on NCR Ranger Chief Hanlon at Camp Golf. It's easiest to obtain during Return to Sender in Camp Forlorn Hope (NCR). When you confront Hanlon, choose to turn him in and he will accept. Afterwards he gives a speech and promptly commits suicide in his office on the first floor. Open the office and pick up the super-powered revolver for yourself. Note: You will lose a little Karma because you have to steal it even though he is dead -- it is lying on the floor. It does well over 100 damage when guns maxed out.
The Rat Slayer: In Freeside, go to The Atomic Wrangler Bar and talk to the female bartender. Ask about getting a room, but instead of paying the 10 caps, ask if you could work out a deal. She will give you a quest in which you have to collect the debt of 3 people throughout Freeside. One the them is named Lady Jane and can be found by the entrance to New Vegas in the day. When you question her about her debt she will say she doesn't have the money, but a carvan of her's in a place called Broc Flower Cave does. If your Speech/Barter is high enough you can convince her to cough the money up, but for the sake of the weapon you will want to go to the cave. She will warn you about the Rodents of Unusual Size (A Princess Bride refrence). Once you arrive at the cave go down the path to the right. A dead Brahmin on the left of the irradiated dead end has the money. To the right is a semi-hidden passageway upward to to 2 or 3 R.O.U.Ses and a stockpile of supplies including The Rat Slayer, an unique Varmint Rifle.
Recompance Of The Fallen: Recompance Of The Fallen is a unique weapon found in Cottonwood Cove. It is a pair of brass-knuckles/spike knuckles made of Dog-Tags. It can be found in the desk of the top floor of Aurelius de Phoenix's office building just inside Cottonwood Cove. It has high damage and diminishes slowly in condition.
Tesla Beaton Prototype Weapon: This weapon is found at the site of the crashed Vertibird. It can be repaired for 11,000 to 12,000 caps and will do up to 108 damage. When trying to get to the weapon, be wary of the hardened Mister Gutsys and hardened Sentrybots.
That Gun: That Gun can be found at Novac gift shop on a metal crate. Buy the storage key and you can steal it. Submitted by Humanoid97.
This Machine: This Machine is a unique rifle that uses .308 ammo. You can get this weapon at Camp McCarran by talking to Col.James Hsu about things going on around the base. Next talk to Lt. Carrie Boyd and help her find some missing supplies. She'll point you in the direction of Sergeant Contreras who is in the supply shack in back of McCarran. Hack his computer and report back to Boyd. She'll give you this weapon.
Thump Thump: At Nelson, after you get into the base, help the leader with the ant problem. Once your down there, look for two generators. Don't go to them, but go right to the other side to find a skeleton with the Thump Thump and around 20 or 30 rounds.
Vance's Gun: From the ransacked caravan near the north of the map, head south and follow the road. On your right there will be a shack called The Wins Hideout, head inside and talk to the Vickie and Vance wannabees if you wish -- you will need to kill them in order to open their safe (and have a lockpick skill of 100). Inside is Vance's 9mm Sub Machine Gun. You can also steal Vance's Lucky Hat and Vickie's Bonet from the corpses.
YCS/186: The YCS/186 is a unique Gauss rifle and can easily be obtained by killing a group of mercenaries northeast of Jacobson Town and north of the ransacked caravan on the road to Jacobson Town. If you know where the aliens are, the mercenaries are nearby. There is a catch though: You must NOT take the Wild Wasteland Trait in the beginning of the game, if you do, they will be replaced by aliens.
