Not true. Just have to look. There is a 2006 Z06 with under 20k miles on it H/C/I etc for $37k obo on CF right now.
Mach 1 over a C6? I could never do that, but they are in different price brackets so unfair comparison.
Perhaps I need to pay more attention to that market. Just 6 months ago anything even worth looking at was still around 45k.
Anyhow my point about the Mach 1 had nothing to do with the superiority or inferiority of the Mach 1 vs a C6 Corvette. Instead my advise for the OP was to buy the cheapest toy he can so that he has more money to do stuff with the toy.
He himself stated that a car in the mid to upper 30K range is going to significantly eat in to his budget. That's not only not smart from a financial perspective, but it will also make it harder to actually have fun with the toy, which is the purpose. While the Mach 1 isn't "better" than a C6 or C5 in any measurable term, it's not inherently less fun, as fun is what you make of it. The price difference is enough however that he'll have more liquid income to have fun with (car or otherwise) if he chooses the cheapest option.
If you had a choice of C6, C5z or Mach 1 and all of them were the same price, I'd choose the C6 all day, every day. That's not reality though and at around 5-10k cheaper, he'll be able to do a lot more with the Mach 1.