Your skill level and comfort level will dictate your pace, which will in turn dictate wear and tear on the car.
Granted it's not an M3... but my 2012 Mazdaspeed3 (3281lbs curb weight vs 3,704lbs for E92 M3) has 11K total miles and I've done 2 trackdays with it at Road Atlanta (Intermediate skill level):
Both were 2-day events (around 200-220mi of track driving each event)
I'm still running the stock tires (Dunlop SP 2050 - 240AA treadwear) but will probably replace them for the next event (March).
Still on stock brake pads/rotors. The former WILL be replaced before the next event (March) if I'm still on this car. I do drive rather 'spiritedly' on a daily basis however.
Otherwise, costs were just oil change/gas/track insurance/event registration. Not sure how that helps, but given the M3's added weight (and faster), you'll likely go through pads faster. That'll also depend on your abilities though, corner entry speed, etc.
How many miles are on your current setup? (Pads/Rotors/Tires)
Tires are also dependent on treadwear/compound type. If you're on a high-mileage tire, you won't tear through them too fast... but your grip won't be too great either of course.
You'll have a blast at the track - Get ready for a new addiction!
"Its only after we’ve lost everything that we’re free to do anything"
Current: 2007 Corvette Z06 (DD/HPDE)
Past: 2012 MazdaSpeed 3, 2007 BMW 335i E92 - 2001 Corvette Z06 - 2001 Camaro SS - 2007 CBR 600RR - 2003 CBR 600RR Racebike - 2001 CBR F4i