Is it a bit different for bicycles though? For a car, you'd go to a dealer and buy a used model. Pretty much all car dealers have lots of used cars on their forecourts, and if you want a particular one, the dealership network for that make can access their computer system to search their network for you. This makes the process practical and doable within a sensible timeframe (not for all cases though, vickster's case for example). For buying a used bike (not the exact make or model, but something pretty similar), you're basically looking at trawling ebay, visitng sellers who are less than truthful about the condition of what they're selling, and buying a bike with no warranty or comeback.