Assuming that shopkeeper identification services have been implemented: Shopkeepers of stores besides general stores will identify any item that can be sold by their shop for a fixed price. General store shopkeepers either don’t identify anything, or can identify everything for you with an exponentially increasing price.

Something would have to be done to avoid trivial item identification of items that shopkeepers sell only one or two of in a class (e.g. showing a bunch of potions to a delicatessen shopkeeper, they reject most of the potions as ones they wouldn’t sell, and informally identifying the potion of fruit juice by not rejecting it). Perhaps they should only offer identification for items for which they sell the entire object class.