I'll sponsor you into a Porsche HPDE. You'll go in as D class with an instructor but it's a great start.
Oil cooler is a must.
Dot 4 brake fluid…( mogul 600)
Good level pads
to run you'll need to have an inspection done too. I can email you the 2013 form I have.
Proper SA2010 rated helmet or you can rent….I guess if you autocross you probably have the helmet.
I know this seems like a bunch of stuff but when your on the track with sometimes $250k cars there's a a strong effort to minimize trading paint risk. It's pretty fun to pass a Ferrari or Audi R8, Viper…. GT2s
but it's all about the driver not the car
I think the cost is ~$250 for about 2.5 total hours of seat time driving (~30 minute sessions per run group) and the cost also includes lunch.