I've got a couple of Craig's List RSS* Feeds that I've been following for a while. One thing I find on there is people asking less than 40-50% off retail for a product that's clearly been used. For example, check out this bike rack. This car rack has been sitting on a car for 3 years in the Virginia area (roof bike racks are notorious for rusting out after a year or so out here) and the owner is asking 33% off or "Best Offer" for the rack. I'm pretty sure someone could find a comparable deal online for a new rack.