Merchants sell a variety of different merchandise. The particular merchandise they sell depends on what kind of merchant they are. Items can also be sold back to merchants, however merchants pay only 10% of the standard price--a significant amount than what you would pay to buy the item. For this reason, using the warehouse to transfer items, no matter how inexpensive, to other characters is well worth the 5% commission.
There are the following kinds of merchants:
|(Foods, Potions, and Scrolls)|
There are also Professional Traders but they only buy stuff, and don't sell anything.