Building anything from the ground up takes an exorbitant amount of money (brakes, H/C/I, complete
suspension) and either enough time to do it yourself, or still more money. And the worst part is that it would be a year or more before it was ready. As you said, I need something turn-key.
The C5 corvette is a great idea. You're right, it's already decently powerful, nice brakes, and a better
suspension. It's just that in my case, I owned one for 10 years and tracked it at the Nurburgring many times. Been there, done that, and unlike foxes, I'm tired of that particular car. My next Corvette WILL be a C6Z.
And... Yes. Much as some would not approve, a 10-15k dollar car that I could track would be phenominal! That's a value that I would not be afraid to run to its max and that would in turn be a lot more fun. So, I would track the hell out of the calypso if I got it. That said, I don't know if "track car" is fair. I would drive it on the street, too. And honestly, I can't see being at Laguna Seca more than 5 or 6 times in my 2 years here.