I think my favorite, though, was the last time I did a yard sale fundraiser with the youth and the professional yard sale people would still want to haggle over things priced at a quarter. Some people have a need to feel the thrill of haggle victory, I guess.
In that case, price it double what you want. You're then free to let it go even if they offer "half", and they go home happy thinking they scored a deal with their haggling prowess.