Setting the price right is the trick. If you want $200 out of something, list it for $300. Usually whatever you're asking, they will start at half. Then you can wheel em into the $200 easy as long as you sandbag it pretty bad like it's killing you to let it go for that. Then you get people who would say $100 or less. Those people, I like to say "If you want it, it will cost you $350, just for the insult!" They either walk off and you never hear from them again, which is a good thing, or they get their head out of their ass and start negotiating closer to your price you really want for it.
Another trick I learned, if you place a wanted ad, dont put out there what you're willing to pay! You could get it for alot less if you dont.
Alot of times if I want rid of something I price it fair to begin with, just to get it to move. If someone tries to say they'll give me less than what I think is fair I just wont do business with em. The right person will come along who will know a fair price when they see it. Of course me being highly antisocial doesnt help anything. I dont like wheeling and dealing with people at all.