Why do so many people assume a Shelby is as costly as it is for the performance? For a long time now the majority of the money you pay for a Shelby has been for that Shelby name, not the performance. It's no secret at all that if you want performance, you buy the standard GT with the options you want, then take your money and mod the car to your taste- you'll end up with a car exactly how you want it and one that cost less and performs better than the Shelby. When I was at a large Mustang show last year, the autocross was interesting because the standard 2009 GTs were only slightly slower around the track than the 2005-8 Shelby models.
If you want a good reason to buy a Shelby now, it's to hold onto it until he dies then sell it at markup with the inevitable price surge. Morbid, but it's going to happen.