My own preference would be for the charisma of/attitude to the character with whom I open dialogue with the vendor to determine prices, rather than automatically picking the best. But once I’d opened dialogue to be able to switch and trade from other characters’ inventories without then using their charisma/attitude. I’d just handwave this as them passing stuff via the character I’d started with.
"You may call it 'nonsense' if you like, but I've heard nonsense, compared with which that would be as sensible as a dictionary!"
