I bought a CD ROM drive for a laptop computer, and have sold quite a few items. Always had very good luck. When I am selling, I always specify that I want payment before shipment, but if the buyer has a good track record on e-bay, I send the item before I receive payment. I've sold some exercize and sporting equip. for about 70-80% of what I paid for it new.
Never been burned yet. E-bay's system makes it pretty hard to screw somebody if you ever want to do business on e-bay again.