I believe that filter is the same thing as what is now the Fluval 105. The 105 sells locally for about $100, a little cheaper online. I'd say fair price depends largely on how easy it is to get parts for. I'd think you could get easily $50 for it if it's unused. If you ask much more, you're getting too close to the price of the newer model IMO. It's a wonderful filter for something in the 10-15 gallon range.