Fallout 3 merchants

Merchants can be found at various locations throughout the Capital Wasteland, the Pitt, and Point Lookout

Background
Most towns in the wasteland have merchants selling food and drinks, with those in more prosperous settlements also offering weapons, armor, and clothing. Doctors can treat various ailments for a fee, and certain traders can repair the Lone Wanderer's equipment.

In addition to these traders, there are also four caravan merchants traveling the DC wastes, with one dedicated to food and chems, one to weapons, a third to armor, and a fourth to junk items. Other wastelanders can be found selling random, and sometimes rare, items. Special encounters with doctors, chem vendors, and hunters (food vendors) are also possible when traveling. Due to the transient and vulnerable nature of traveling the wasteland, it is advisable to consider the caravan merchants and wasteland scavengers a temporary system of bartering meant to be used early in the game.

Merchant inventories will scale with the player character's level, although certain advanced items such as power armor and plasma weapons will not normally be available. Prices are the same from store to store, but can also be affected by the player character's Barter skill.

Merchants will have a new inventory at 12:00 AM every Sunday and Wednesday.

Any caps paid to merchants can be found in their inventories should they be killed.

Merchants

 * Merchants are not affected by any SPECIAL bonuses from equipment or items they use. However, they are affected by the equipment they use that directly adjusts a specific skill, such as Barter or Repair.
 * Any items sold to merchants by the player character will remain in their inventories until they restock.
 * Though merchants will buy any items the player character offers, most specialized merchants (such as doctors) will not display items sold to them by the player character where those items fall outside the category of their specialty. The consequence of this is that items sold in error will not be able to be bought back if the item being bartered for is outside the merchant's item specialty category.

Merchant overview
1 Sells Mesmetron power cells only.

2 Glitched, see Haley's page.

Caravan merchants
Caravan merchants are named roving salesmen that carry goods across the wasteland. They travel accompanied by a single armed caravan guard, and a pack brahmin.

Crazy Wolfgang, Crow, Doc Hoff, and Lucky Harith can be encountered on their trade routes, stopping to sell their wares at various locations. Each merchant specializes in a specific category of items, and also offers repair services. Attacking any caravan merchant will result in all four caravan merchants refusing to trade with the player character.

Caravan investment
At Canterbury Commons, Uncle Roe offers the player character a map showing the paths of the merchants and their various trade stops. He also gives the option of investing in any of the caravans. The player character can choose to invest twice in each merchant, with 200 and then 500 caps (or 100 and then 250 with the Master Trader perk).

Investing in a caravan allows that merchant to sell a wider variety and higher quality of items, and increases the number of caps they have available when trading. It also raises their Repair skill (up to 75 in one case, with the second investment), allowing them to restore the player character's equipment (i.e. weapons and apparel) to near perfect condition.

Caravan guard overview
All caravan guards are equipped with R91 assault rifles and leather armor. They are significantly better combatants than most other human non-player characters and are roughly on par with a non-player character companion or super mutant master in terms of durability.

Caravan routes
Each caravan follows the same route across the wastelands. They often use roads even though the roads are dilapidated. In order of travel, the merchants stop just outside each of the following areas:
 * Canterbury Commons
 * Temple of the Union
 * Agatha's house
 * Paradise Falls
 * Arefu
 * Evergreen Mills
 * Megaton
 * Rivet City

The merchants cycle through the caravan waypoints in the same order: Doc Hoff, Crazy Wolfgang, Crow, then Lucky Harith. They move around the game world at different rates depending on whether time passes in real game-time or wait-time. For example, when looking at Doc Hoff and using the Wait feature to jump ahead two or three hours, Crazy Wolfgang will appear there instead. However, if one does not use the Wait feature and actually stands there in real game-time, no one will appear for the next five+ hours.

Even if the caravan owner and bodyguard are dead, their pack brahmin will still follow the trade route. However, the brahmin offers no interaction options. Even if the key to the merchant's inventory is looted from his body, the dead merchant's inventory will never restock on the brahmin.

Caravan death and injury
Caravan merchants have more health than standard non-player characters, and their caravan guard bodyguards are significantly tougher than normal, even wearing their basic leather armor. Both the merchants and their guards also carry a couple of stimpaks for healing wounds in combat. Pack brahmin have a large amount of health, considerably more than a regular brahmin.

Nonetheless, caravan merchants are still susceptible to death due to the dangers of their routes: deathclaws, yao guai, Enclave soldiers, raiders and super mutants. Although the merchants usually slip by the danger if the player character is not in the area, caravans may be attacked any time they are in the same area or cell as the player character—regardless of whether they are visible or not. Certain areas of the route are extremely dangerous. For example, the route from Megaton to Rivet City goes past Arlington Library and the Citadel, through Central DC, and across the super mutant-infested bridge across the pipes leading into Jefferson Memorial. As one progresses along the main quest and achieves higher levels, the more powerful monsters will take a toll on the caravan merchants. The Enclave will establish camps directly on the caravan route or near enough to produce an encounter, like the large camp controlling the crossroad south of the Temple of the Union, which will pose a problem if the merchant approaches the camp while the Lone Wanderer is in the area. Late in the game, it is not uncommon to see a lone merchant without either their pack brahmin or guard.

One can check to see if a merchant is dead by talking with Uncle Roe and asking to invest. It is not possible to invest in a dead merchant. Any surviving bodyguards will hang around Uncle Roe's house in Canterbury Commons. A dead pack brahmin, however, may respawn. If the caravan merchant's brahmin survived, it may still be encountered, fully stocked, and wandering the wasteland.

Increasing caravan survivability
Players may be able to stave off the demise of a caravan merchant by various means. Methods by which players may do this include forcibly providing better equipment to the merchants and their bodyguards (see Pickpocketing and Pickpocketing), pre-clearing areas where they travel of enemies (See locations that fall on caravan routes and Enclave camps), purposely spawning only friendly random encounters along their caravan routes (see random encounters and their locations), and avoiding entering map cells that they travel in altogether, when at all possible.
 * Caravan merchants travel regular routes that at times, take them dangerously close to hostile enemies. Care should be taken not to trigger hostile encounters at random encounter locations occurring along caravan routes.
 * Hostile human enemies enslaved via the use of the Mesmetron and sent to Paradise Falls will not respawn. This allows the player character to remove dangerous Enclave, raider, and Talon Company hostiles. The negative consequences of participating in the slave trade still apply however.
 * If one sees a caravan near an unsafe place, fast-traveling away may prevent the threat from injuring the caravan.

Bugs

 * In some cases, the merchants will all stop moving along their routes. This appears to last the entire game and does not prevent the player from trading with them if they can be found. While the player can no longer wait for the merchant they want, the advantage is that they will no longer have to pass enemy camps, greatly increasing the chance that the merchants will survive.
 * This bug was fixed at least once, on the 360, by finding the location of every merchant, then fast traveling rapidly between them and then to other areas (as quickly as possible). Eventually the merchants began to rotate through their routes again.
 * Another way to fix this bug is to meet Ben Canning and give him water. After 1–2 hours he will leave and take the same route as the merchants, thus unlocking all the subsequent caravans. On the other hand, if one doesn't want this bug to be fixed, simply don't talk to him and leave him alone.
 * After installing the 1.4 patch and starting a new game, the merchants seem to appear alone without a guard or brahmin escort.
 * When a caravan merchant is traveling alone, without a guard or brahmin, it may be a bug where the guard and/or brahmin is too far away from the caravan to spawn with it when the player waits outside of a city. In order to fix this simply run to the caravan and wait for him to greet the Lone Wanderer. In the middle of the greeting click wait, then wait for 24 hours or so. The caravan guard and or brahmin should now be with the merchant and will travel and spawn with him.