I usually try to bundle a few things at garage sales and it adds some juice to the bargaining. But, when I sell a car in a private sale I tell people the "price is fixed at X dollars" and that seems to eliminate the issue. If I have a car on the block it means I'm done with it and want a quick sale and I price it low. The last Taurus I sold I threw in a couple quarts of oil and a spare belt and that sealed it. The guy just wanted to see something out of me so I went along.