I have a 2005 Chevy avalanche, and i need a system. in the avalanches you can build a box that is in the bed of the truck but you take off the back wall so it is viewable from inside the truck .this means you can fit pretty much anything in it(for those of you who didnt know).the custom box costs about $500-$600. Including mids and highs what is the absolute best system i could get for $1500?.