It would be great if you could set up a couple bins which would let people sell things to you (like empty vials, full elixers, groups of herbs?)
People could put some gold into a a little box and when ever someone took one of the items there (It should be able to be kinda subjective.. Like a weapon with stats at/above/below a certain level Vials above a certain number of months left) some money pops out for them.
Kinda like the Trade Ministry in that it won't use ALL your gold, only the gold you assign to it. Make sense?

Whats the point?

You own a shop to make money, not give it to other people

If you want empty vials or weapons with certain stats, you may as well just go find a forger or someone that uses a lot of vials.

Maybe, but there are plenty of people (e.g. novices, rogues, maybe) that don't have an immediate buyer or source for empty vials and other goods. This could provide those people with a quick, easily accessible way to get rid of or obtain more.

I suppose you'd be able to specify which items you wanted to purchase, within limits - say, I could advertise that I wanted rubies, faeleaf, elixer vitae, and four or five more things - and then buy or create some way to let people know what you're looking for (a form of shopsign, I suppose, or just a flame-sigiled letter).