DO NOT BE AFRAID TO SAY NO. People think its rude to do that shit, if they want 25k for a car worth 22.5k and they won't budge, you say "thanks anyways." If they're dicks, remind them that they're losing a sale.

Salesmen know exactly when they're losing a deal, and if you make them feel like it isn't going their way, they may cut you some slack. Unless its like a saleman with balls of steel or something...

BTW, offer them something low as hell, to show them that you're cheap as hell. They know not to flash big prices to a cheap ass.