I have sold mine, which had the same specs as yours, for about $700 (after fees + shipping) on Amazon Marketplace just 3 weeks ago.
I would say that depending on the condition, it can sell for as much as $650 (again, after fees + shipping).
Cosmetically, mine was like-new as it had a hard-shell cover and keyboard cover since the day I got it. I also provided my Speck hard-shell cover/Lion Pre-Installed/Office 2011 free of charge.