Your mistake was getting the latest technology. It's like buying a brand new car - huge depreciation. Today's $3000 gamer rig will be ho hum in a couple years. I think all you can do is replace the video card with something that will work (not necessarily the best card) and sell it for what you can. Try Ebay with a reserve that you could live with.
Try
www.newegg.com for a video card.
Good luck.