Good suggestion for how to get better gold from vendors. Still, the point is that the price shown should be the price paid. Not some random percentage higher than that amount that I am currently uncertain how charisma and other factors affect. I, for one, do not miss the usual US system of adding tax at the register (shown price: $19.99, price at register: $21.44) instead of like, say, Norway, where the price on the item is the price you pay.
Looks like I'm moving to Norway then, cause I hate the US system too.