The reason I always suggest crutchfield is for the step by step(and I mean
step by step) instructions and diagrams of your specific car. They also have GREAT customer service(this means alot to me). I buy most of my head units and door/dash/back speakers from them, if I plan on installing it on a car I'm not familiar with that really helps. They will help with amps and such if you call them(I don't know jack about wiring an amp). I bought my infinity amp and speakers from them. I bought the subs and eclipse amp from the audio shop because they gave me 'alittle' break on the install and box if I bought from them.
You may have found the best deal on that amp but you may want to check
www.pricescan.com , just to make sure.