This is exactly the sort of thing I like bringing back from Serbia: small enough to fit in a bag, but specific enough to remind you where you bought it. Small bottles are best. A local scent, soap or oil feels personal, but it is still easy to pack and usually does not cost airport-perfume money. It is also the kind of thing you can talk about when someone asks what you brought back, because there is usually a little story attached to where you found it.