Each Town has Vendors that will sell armor, weapons, potions, keys, tomes, and will repair. To see if an NPC has something to sell, click on them, and look for Trade or Trade/Repair.

Faster Sell Trick!
You can sell an item to an NPC without the confirmation by control-left-clicking on items in your inventory. Be careful with this as you might sell something by mistake. This command is for experienced users!

How can I reset the Vendor's Inventory?

In single and multiplayer, regeneration occurs as follows:

1) All players have left town
2) If not all players have left town, then any NPC who has not been (and isn't currently) trading with any player for the previous four minutes
3) The Gamble stock is regenerated each time a player clicks the Gamble option. If another player comes to gamble, he will see the same items as you and he must leave that screen before new items show up.

Note: a Vendor's Inventory is reset if you leave town but not the act. For example, it won't be reset if you were to leave the Rogue Encampment to go the Bloody Foothills, while it would be if you step out of town into the Blood Moor.

Will Different Vendors pay more or less for an item or do they all buy an item for the same price?
They will all pay the same price for an item. You do not have to wheel and deal.

Can I buy back an item if I accidentally sold it?
Sometimes, however if you do not see it on any of the tabs or pages, you are out of luck.

What is the maximum amount of gold a Vendor will pay for an item?

Normal Difficulty

Act I: 5,000 Gold
Act II: 10,000 Gold
Act III: 15,000 Gold
Act IV: 20,000 Gold
Act V: 25,000 Gold

Act I-V: 30,000 Gold

Hell Difficulty:

Act I-V: 35,000 Gold, the maximum gold a vendor will pay you for an item.

If you find you have reached the maximum amount of gold a vendor will pay for an item, but it has not yet reached 25,000 or 30,000 save the item until the next act or difficulty level to receive more gold for your item.

Vendor's Inventory and Difficulty Levels
The vendor's inventories are tied to the act, difficulty and character's level. As you reach higher character levels, acts, and higher difficulty levels new things will be available. Also, the chance will become greater to find Exceptional and Elite Items in the vendor's inventories.

The Inventories of the Act I and Act II Vendors in Hell are not upgraded, except for the Throwing Weapons. No other Exceptional or Elite item will be offered. Gambling is unaffected.

Repairing Items
You do not receive more money when selling if you first repair the item before selling it.