I don't understand why one would be concerned about "pissing them off". It's business, they certainly have no reservations about pissing you off when you go in 3 yrs later and they tell you they want to steal your car and that it's not worth anywhere near what you thought.

Forgive me, but one shouldn't ask if they will take x, one should TELL THEM one will pay x and be prepared to walk away if they are abusive or otherwise disrespectful. Who cares if you piss them off, you're there to buy a car and they're there to sell a car, what's to be pissed off about?