If you net $4k a month then that is more than enough for an M3 if you are in a stable financial situation. But like I said, don't cheap out. I've driven these "budget" M3's when I was shopping for mine and I can tell you without a doubt that the experience behind the wheel of a ragged out M is nothing like driving a well maintained one.
If you are anxious about spending a lot then the ZHP would probably be a better choice. An M3 will not kill you in maintenance cost if you can DIY, but you have to remember that it was an expensive car in its day. The entry price is low now, but the maintenance costs are still high. ZHP is much more reasonable. It comes down to how much of your income you want to spend on buying and maintaining a vehicle and how comfortable you are with the chance that you could run into an unexpected repair that could cost a lot like the exhaust hub failure.
Last edited by choxor; 12-05-2012 at 12:48 AM.