When negotiating a deal, make your offer, listen to the response and walk away (not rudely, just…you have somewhere else to be). The first one who calls back loses. This works well for buying a car.

Edit: oops, hit submit too quickly. I used this to buy an ATV long ago and many cars since. "I can spend $XXX (know this nunber before you start). <wait for counter offer>. It’s a nice ATV, but I promised myself that I’d spend no more than $XXX. Thank you for your time. "