I think the Shelby is a fair buy at MSRP, the C6 is a fair buy at MSRP (of course, now you can get those all day long for invoice + a few hundred), and the Z06 is a fair buy at MSRP. Both Ford and Chevy are offering good values for the money. It's when people justify paying heavy premiums for the iron that it gets a little weird. The build quality, craftsmanship and materials used in Corvettes and Mustangs aren't exactly premium, so you're basically paying for great performance and engineering on the cheap, and image. I think the factory prices are in-line. After that, it's a circus.
Comparing a Corvette to a Mustang has always been, and always will be, ridiculous.... All you have to do is pull the outer skins off of both cars, and you see that the Corvette is a race car for the street, and the Mustang is a street car you might be able to race.
Two different things, and both are admirable and valid within their own right and category and ultimate purpose.
A sports car can play double-duty in the muscle car league, if it's got enough juice under the hood and enough stoutness in the driveline to offer good drag-racing utility. The Corvette qualifies..
But a muscle car cannot play in the sports car arena unless it's got the chassis, the packaging, and the physical stats (weight, bias, balance, etc..) to be an effective tool in that discipline. The GT500 does not really qualify. It didn't in 1968, and doesn't now. That's not knocking the car, I just don't understand why people try to make it into something it isn't. It's probably amazing how CLOSE a GT500 may be able to hang with a Corvette on a road course, but..., just take it for what it's worth, it's no sports car, it's no replacement for a sport's car. It's a muscle car, a big 4-seat mega-power open-road bomber.. You can bench race, and play the numbers game all day long. But when you actually DRIVE a Corvette, and then a Mustang, you realize that the experiences behind the wheel are apples and oranges.