I would look on some places like EBay to get an idea on pricing and either sell it there or list it in the Tom's Hardware Classified forum -- but do read the rules of that forum before you post as they require some specific information and photos. Sometimes if you aren't too sure you can price things at $xxx or best offer and see how it goes.
If you check out EBay, search by the exact model and hopefully they will have some used models there.