Sorry I missed this thread on Saturday. I was out of town and then digging into the guts of a Cambridge Soundworks, Model 11 yesterday. I snagged for a song!
eBay will let you end a listing for any reason up until the last 12 hours of the listing. At least that's the way it worked a few years ago. You still get charged the listing fees but not the final value fees, which are typically the higher of the two. You could even ask them to refund those fees as the item you were selling "developed a problem" that rendered it unsellable. Since the listing ended with a high bidder, you might still get a negative feedback hit. If you do, be sure to leave a VERY PROFESSIONAL reply to the winning bidders comment. Something like, "Sorry for the no sale, customized items sometimes have issues."
I agree with everyone else, keep that bad boy!! It's the prettiest 700B I've ever seen!