Shopping
Buying items from the NPC merchants, the three artisans, will be a major occupation in Diablo III. How important the actual buying will be isn't yet known; it seems that the D3 Team's goal is to keep players down in the dungeons as much of the time as possible, so shopping will probably be a fairly minimal activity.
NPCs will far more often provide item services; socketing, unsocketing, crafting of various types, and they'll also buy up items from players; what isn't salvaged in the field, at least.
Shopping Interface
The NPC shopping interface occupies one tab on the larger NPC interaction window. You can see a sample of the Blacksmith's wares in the image to the right. The selection is minimal since the character in the screenshot is a low level Barbarian. Later in the game all sorts of blue (magical) items will be added to the selection.
It's not know how good the shopping items can be; presumably they'll had some potential, but won't rank with the best crafting recipes available, since that seems to be the path players are more intended to follow for item acquisitions. Other than finding stuff from dead monsters, of course.
=Buyback Window
One added feature sure to please players is the item buyback option. Anything you sell to the NPC merchants can be bought back. This isn't something players will use often, or on purpose, but that one time you misclick and accidentally sell something you wanted to keep, the buyback will be a blessing.
There does not seem to be any un-salvage option though, so be careful what you stick into the salvage cube.
Scroll of Wealth
Further reducing the importance of actually returning to town is the Scroll of Wealth. This new feature lets a character sell off all of their unwanted items from any location, just as if they were standing in town at the Artisan's wagon.
