Well, tying in my "reliable" stipulation, it must be relatively cheap to run, and I don't really have a fixed purchase price in mind, but if it's old, it will likely need several thousand dollars in cleanup/repaint/repair.
There are two scenarios playing in my head right now, one is to get a new car in about a year and a half (going into the summer of 2011), the other is to wait until I graduate (May 2013, tentatively) and get something really nice. For the first line of thought, let's go with $15-20,000 maximum purchase price, the latter $35,000.
The prevalent idea right now though is to just hold off until post-graduation and lease something like an M3 or the next generation S5. This is pretty far ahead in the running since the car would be under warranty, new, and very quick.
I don't know if any of that really made since, but in short, I'm debating between something old and cheaper in a year and a half, or something new and more expensive in three and a half years.
Was that the most confusing answer you've ever gotten to such a simple question? Probably.