Just one of these can play crysis on medium/high and fallout 3 perfectly and SLI'ed they can play crysis on high no problem. I've never seen a game that i can't play on ultra high exept for crysis. Exellent value and performance!!!
Well, considering you can get a 9800GT starting at around $110-$120 and a 9800GTX starting around $150, I would say you need to drop your price to atleast $100, if not less.
Now, I will tell you that you will make more money on Ebay than you will here. People here are pretty informed on performance/cost and aren't willing to shell out the same amount as a brand new card that is going to be a bit better.
The 8800GTS is an awesome card as I have one myself and I absolutely love it. Nevertheless, basket has a good point that they should be priced lower than the newer cards. And yes, you will most likely get more on ebay. Good luck.
Oh yeah, the 8800 GTS is a great card... if I didn't have some other parts on the way, I would probably make the OP a reasonable offer.
Who knows, though... the OP might find a person looking for a match to their single card and be able to charge a good price. I didn't realize they were already becoming a rarity (newegg and tigerdirect have none).