What to look for in a track car, that’s a loaded question.
#1 build quality. A poorly built race car isn’t safe. If you see one item that is sloppy then be prepared to find more and more and more.
A current log book and tech inspection from SCCA or NASA means at least somebody inspected the car and hopefully it actually meets the sanctioning bodys safety specs. Not all inspectors are the same so this isn’t a guarentee but it’s better than buying a PT car that has no tech requirement.
Look at the cage and the quality of the welds. Start by looking to ensure the welds go around the full perimeter of where the tubes join. This is a requirement for cage safety and if not done a sign of other short cuts.
Belts, fuel cells and some seats have freshness dating. If those parts are not within the cert timeframe the rest of the car is probably worn out.
Typically it is better to pay a little more for a professionally built car unless you plan on taking on another build project.
What car? There is no absolute answer but here is my opinion.
You gotta have a V8. Who wants anything without V8 torque and sound for a track car? A Miata is probably the most cost effective track car and ine of the best training tools but it’s a Miata so pass. But if you want a lot of track time with less garage time then the less exotic the motor the better. Big hp is great but big hp wears out parts way faster. All parts. Remember the purchase price is the cheapest part of this equation. You have to maintain the car and keep it running. Good oiling and proper cooling are a must so if these systems don’t seem like overkill then pass.
I’m not familiar with SCCA classes but in NASA a nice American V8 TT car or an American Iron or American Iron Extreme car would fit the bill. The Factory Five Cobra class cars look like a blast.
Just bolting on expensive parts doesn’t guarentee the car works. If the car you buy has some pedigree (as in it has documented race wins or low lap times) at least you have a chance that the setup under the car works. A car that handles predicably is priority one. It may not be the absolute “best” handling car but frankly most people don’t have enough track time or skill to really comment on a cars performance. A predictable car gives you the opportunity to learn where the car is failing vs you being the problem and over time you can become fast even if the car is slow.