Question about current "Used" GTX 680 price's

I have been wanting to sell my EVGA GeForce GTX 680 Superclocked Signature 2GB, for quite awhile now. A guy just sold the same model on Ebay for a little more than 400 US dollars. I have also seen them for sale on other sites for 400 and up. My question is WHY?? I don't see why anyone would buy this model for that price when you can get something better for less. The only thing I can think of is there are still people who want one for SLi. Any ideas why they sell for this amount?

This is the card I have http://ift.tt/1PZ4Syq

Question about current "Used" GTX 680 price's