Depends on the item you are selling as well.
Some items are hot stuff, like for example my previous U2410 Monitor by dell. It was a second hand item but condition was still really good. Sold it off for RM600, half the price i bought it.

Your description must be honest as well.
Reason for sale must be there, otherwise people know you are scamming.

And of course, sometimes you just have to wait. Until today i can't sell off my modem and a brand new Jaybird Earphone.