Originally Posted by Transfer
Our cars are popular for track use, with good reason.
It's not just popular for track use, it's a car whose existence can only be truly appreciated on the track -- even more so than other cars. Does the M3 also make casual daily driving more fun than other cars? Of course. But you just don't understand how much better an M3 is than all those other cars (and how much fun you can have in it) until you see what it can do out there. Not even twisty canyon roads come close to delivering that sensation.
I don't think the added cost of an M3 over a 335i for example (even ignoring the higher running costs) are justifiable UNLESS you take it to the track occasionally IMHO. And yes, as others have said, if you're going for your first few times you can run it bone stock and be fine. As you get faster (i.e. get better versions of the "driver mod"), the first thing you'll need to get is upgraded brake fluid, then brake pads, then maybe larger tires with a square setup and possibly even grippier summer tires that wear faster, or up to R-compounds once you can handle them. After that you'd be looking at suspension mods (camber plates, coilovers, etc).