For good sound but cheap as hell, go with bluapunkt's entry line ( models PCx402 and PCx542 for your car). I started with a similar model and for the money they cannot be beat. You'll spend under $70 to have them in the entire car. I assume you'll be installing them yourself, which saves a good deal of money and is easy.
<span style='color:gray'><span style='font-family:Courier'>1995 e36 3 Series RIP
1999 e46 3 Series BURN IN HELL
2000 MR-S Roadster= Current</span></span>