Don't worry about rust whereas these cars are constructed using an aluminum full cage type frame. Exhaust systems are the only possible "rust" items on a C4. Tires (16") are becoming a replacement issue, as the correct size are becoming harder to find. Optispark is the only real pain-in-the-butt problem that can arise (LT-1), and can be addressed as per the info mentioned in the previous comments by members above. Try for lower mileage cars, but watch for tell-tail abuse indications, such as sloppy u-joints, worn seat bolsters, worn clutch or brake pedals, even wear spots on the steering wheel. An abused lower mileage car is no match for a well maintained higher mileage one! Check for plastic trim pieces, cracks,wear etc. These tend to dry out, can be fragile, and can cost a few bucks to replace. For $15000, you should be able to get a fairly decent Vette, just beware of the junkers asking stupid prices. Any partially disassembled or altered cars...stay away from!!