here's my suggestion. Wait a couple of months for the 335i's to get traded in. usually the guys who have way too much money to throw around will get them, keep them for about 6 months and trade them in with like 4K on the clock. It'll get CPO warranty extension and you'll still get the original factory warr/maint to 4 years/50K. (CPO Limited Warranty is 6 year/100K) Maintenance can also be upped to 6/100, which i really suggest doing. First brake job will pay for itself.
You can go 2 or 4 door, but for insurance costs, and rigidity factors, i would go with the sedan.
The E39 M5's that may still have warranties on them, may be a couple K out of your price range, and the 03 and newer M3 is still going to set you back about 38K with all warranties on them.
In your price range, i really suggest BMW just for the fact that the Maintenance Warranty adds that much more to the deal. You can get a 350Z but you're going to be paying for the oil changes and brake jobs and such, and that will get spendy if you end up with the track model with the Brembos.
The Z4 3.0 or the new 3.0si would also be a great buy if you really want the 2 door, and chicks dig convertibles anyway
the new ones have the new 255hp engine but will cost you more to insure over an 03 or an 04.