Has anyone ever purchased a driver C2 Roadster with a a bad frame (knowingly or unknowingly) and what would be today’s value be for a car like that?

 

Welcome to the forum. It depends in part on the condition of the rest of the car and what options were included. Probably the best way to determine this would be to start with the value of the car once it had been finished and work backwards on parts and labor to get it there.