You might be able to score a toyota echo for $1000 or maybe a bit more.
Also suzuki swift.
Hyundai Excel.
toyota corolla
If you want to stick to the super small car theme, Ford Ka.
Oh and when you want to put a subwoofer into it, look into the Kicker CompVT 6.5" range of subwoofers. (If you would want to do this that is.)
They put those on motorbikes.
![Confused](/forum/images/smilies/confused.gif)