Monitoring the way ebay bids pan out on used bikes, the average follows the basic pattern of depreciation of 35% from the manufacturer's suggested retail price on the first year of use and 10% every year thereafter. Overall, the auction participants follow the time-honored traits -- bidders get over-excited and the sellers act like they deserve every penny coming their way.
Best deal on an amazing piece of engineering: the $25 dollar BikeNashbar clipless pedals. I also received a new pair of XC skate bindings in the mail. One of my currently installed bindings gave out last winter on the clap mechanism. From the looks of it, the makers of the binding, Salomon, actually reinforced the mechanism that broke on me, providing me hope that at least a few companies practice process improvement.