I'm not sure how most games handle this. In the ones I have been in, selling everything happens between sessions (sell for 50%), and you can buy anything mundane. Buying magic items may be something between sessions also, depending on where you are and what is available. The DM may set a max value or whatever that is automatically available. Above that, it may have to happen in session, or at least with some minimal DM interaction. It is pretty easy to find things online (d20pfsrd or AoN), so generally (in my experience anyway), the DM doesn't really do much with loot at all unless teaching a new player how to enter things on the sheet. The DM will tell the players what there is and it is up to the players to take notes on what is available, decide what is worth carting away, and add it to their sheet. Or not. If you don't add it to your sheet, you didn't pick it up and take it with you. Pretty simple. If you are dealing with something unique, then a handout with an image (if you can find something fitting) and info on the item is probably all you need. Is there something specific that is an issue?
