I am considering pulling the trigger on a 2007 Shelby GT500. I found one for $35K (no sales tax in GA). The owner paid a premium to MSRP ($45K+) and now has 1200 miles on the brand new car.
The clutch tranny problem is caused by a warped flywheel. It is a problem on 2007, 2008, and early 2009 cars. It's called the tranny/clutch TSB. It is covered under warranty, but there must be a problem before Ford will fix it(the first sign of trouble is a vibration). It seems that the flywheel problem transfers to the dual-disk clutch and then to the transmission (if not addressed quickly).
It will be a daily driver and parked outside.