I'm selling two Sapphire Radeon HD 6990's.  These cards are amazing at mining and I wish I didn't have to give them up.  I got consistent hash rates of 744 MH/s each, using CGMiner.  Below, are the eBay links.  The bidding started at $0.99 each and there is no reserve.  Six and a half days left (as of this writing).  Check them out.

http://www.ebay.com/itm/170701175886

http://www.ebay.com/itm/170701176166

If you're interested I can tell you the CGMiner parameters and which drivers I used, etc. to give the best stability and hashrate conditions.  I kept them air-conditioned for cooling.

Please feel free to ask me anything you want to know about them.
Merry mining!