Once again Sam is right. New they cost a fortune. My buddy that raced with me last year with his M5 BMW just picked up some used race 18" slicks for about 500$ and he said the same thing.....for us guys to go and lap our cars these tires are beyond good. But for these racing companies as soon as they test out a few laps with them, the tires are no good anymore.
Lets get serious, I'm no professional. So I won't go spend a ton of money for new tires. Unless I start lapping my fastback every week. Which for now is not my goal. I want to have fun every few weeks at the track and enjoy the best of both worlds with my car.