The main advice is to not pay retail. In my limited experience, the retail price should include a full body massage while they're having PhD's install it. Unfortunatly I havn't found a shop that shares my views.

On the other end of the scale, anyone who's ever had their car stereo stolen will be eternally gratefull if you make a concious effort not to buy stolen equipment. Manuals or recipts would be great, or just someone you trust.

I got my amp from hanging out on a car stereo board while waiting for my empeg to arrive. I found someone local selling an amp they'd gotten a good deal on and bought too many.

Matthew