Best places to buy car audio stuff?

Try Sonic Electronix. That's where I bought all my gear last summer.

http://www.sonicelectronix.com/?affiliate=googadw&gclid=CKSO0I6-4bUCFYk7MgodX3IAmg

Crutchfield is a great place to do research. I wouldn't buy there unless your income can handle their top dollar prices.