Well for what you're asking for I'd recommend the Paasche H. It's a single action brush, which means you won't be able to spray fine lines or anything, but for cars that won't matter. Your paint jobs will depend on your masking ability. It's really cheap, too, $42 for all the accessories you'll ever need besides the air compressor. Here's a link:
http://www.dixieart.com/HSet.html
Free shipping on $45 or more so I'd recommend you pick up a cheapie thing at $3 or 4 bucks to get free shipping.
I myself use an Iwata Revolution double action, I got it for $60. The advantages are ease of cleaning, and ease of maintenance. Here's where I got it from:
http://www.coastairbrush.com/pages/3.html
Hope this helps