Why not just use the e92? Buy a square setup of Apex Arc8's and and Yoko AD08's and let it rip
Cheapest route to make sure you like it and less PITA. You only have to garage/maintain the one car and you get to drive the M3 the way it was meant to be driven. Just change up the wheels before/after the track time and you're good to go. Buying a track only car is a slippery slope and a big investment for an activity you're just trying out. I just went through this last year when I got started and bought/modified a e46 M3 for the track. Great car, but I wanted to go faster so after 4 months and 3k miles I sold it and ordered a new e92 for a track car. All told the e46 cost me $10k for 3k miles of use. I would have been better off just buying the E92 immediately. Just my $.02