If you are really interested in your dream car then no chase the cheapest theory for it. It is your dream and you may afford any cost for it. Just go on an autotrader, they can better guide you!
Go to a local car dealer and find a Mercedes for about $7,000.
Mercedes makes a lot of cool cars.
Check out autotrade.com I believe I got my eclipse from their for fairly cheap.
Craigslist is decent too...
Also a car I see almost every teenager drive is a grand am so you could always go with a straight up black one and be cool like everyone else? xD