A brand new Camaro 1SS 1LE will be $45k. It's the best performance bang for buck on the market and comes pretty much built for track days- it has an extra oil cooler, transmission fluid cooler, great brakes with good street/track pads (they're basically the same as Ferrodo DS2500), and the alpha platform has unbelievable potential. The motor is easy to deal with since it's NA (linear power curve, still makes great tq at lower RPMs) and the eLSD+traction control tuning is extremely competent. I beat the absolute shit out of mine on track 1-2 times a month and it never skips a beat even in the disgusting Florida summer heat.
Best Brake pads for Chevrolet Camaro
Other parts for Chevrolet Camaro