I discovered that if you sell or buy items from the inventory of your highest-cha player, you get significantly better prices. I don't have a big problem with this, but the way it's implemented is basically a tax on my time as a player, because I can tediously transfer all wares to the pretty-faced character and have them do the selling.

Please just make the trader take the highest-charisma party member into account, no matter who happens to be holding the thing for sale.