I Need A Charisma mechanic

[imp_fireball]

Those rules also have something about haggling. Attempting to buy low would be diplomacy, but I think for people functioning as salesmen trying to sell high, they'd be using intimidate, either to combat hagglers or just convince in general.

Note that a car salemen only seems friendly, but he actually is there to make you feel uncomfortable until you do what he wants. It's effectively intimidation.

Selling high with diplomacy would be PR - you use it to represent your company at a seminar or whatever. This is all to increase your reputation whereas intimidate affects it negatively, and that's why car salesmen usually work commission and not corporate side or whatever.