If you're gonna do RP shopping, you gotta establish before the session that's gonna be what's happening so everyone can come up with ways to interact with the scenario.
You also absolutely have to (looking at you in particular, 5e) establish availabilities and exact prices beforehand. The back and forth of "how much does X cost -> I can't afford that" is the biggest waste of time when shopping.
If you're gonna do RP shopping, you gotta establish before the session that's gonna be what's happening so everyone can come up with ways to interact with the scenario.
You also absolutely have to (looking at you in particular, 5e) establish availabilities and exact prices beforehand. The back and forth of "how much does X cost -> I can't afford that" is the biggest waste of time when shopping.
I like to make little cards for my shops with the items on it so I can just hand them out whenever one person goes to a shop