Just a heads up, I sold my almost new MSI 6990 on eBay about a week ago the same way you are (no reserve, starts at .99) and it ended up only going for ~$560 and I only had about $500 after shipping, eBay, and PayPal fees.
I regret not just keeping it now.
Eeesh... thanks for the warning. I did see a lot of variance in the final sale prices when I looked through the auctions that had already ended. Some recent ones went for $700, but other were closer to $600. Fingers crossed.