The answers below all give you the best sites available...but just remember, with the economy the way it is right now, it is a BUYERS' MARKET, there a tons of used bikes on the market right now. Most people think they can sell their bikes for what they are wrth, most used bikes right now are in the same price range as buying a new bike that comes with a warranty. The dealers are struggling and are doing whatever they have to do to sell new bikes. I don't know how much your parents are asking for the bike, but if it's $10,00 or more, they are going to have a very hard time selling it....you can buy a new '09 or '10 model for very close to that and the new bikes are way better, with a bigger engine, fuel injection and a 6-spd trans...AND a 2-year warranty....so....unless they set their price around $8000 or so....good luck.