I can attest to the fact that building a car is very expensive and time consuming. Although its big fun.

If your plan is to have racing as your hobby rather than car building and tuning, then go buy a car that is already set up. If you're looking to timker, either 318 or 325 would be fine. I have a 1989 325is that is IT-S ready after a summer of work. It will not be competitive for another couple of years as I slowly add the components that wil make it go fast. here's my 2 cents.