How do you reset vendor items?

[HardRock]

That's the idea.

To be honest, I think vendor farming will become a non-issue anyway as soon as every item type will drop from monsters, which should happen soon after the beta content. The devs could always take measures to discourage this behavior even more though.

[direfire]

Good question and bad design not to remove an item sold.

[HardRock]

bad design not to remove an item sold.

I disagree. This puts a cap on the cost of Magic crafting components (Rares are removed from vendors when you buy them), so people with ludicrous amount of money won't be able to inflate their price too much.