a pair of sundown sa 12s will sh** on the type Rs when it comes to getting loud. Hell go for some american bass XFL 12s that mylows10 can hook you up with. Add a giant diehard platinum AGM from sears or some agms from sam's club, to the trunk, those are actually really beefy batterys for the price and it'll keep your voltage up high enough. Do the alternator later on. Those yellowtops are overrated, overpriced. Get a soundqubed 2200.1D for your amp or if you want to upgrade later on like running triple 12s if you have the space for it, look for quality 3k rms amp in the classifieds.
high output alternators cost 450-600, you'll have no budget left for anything decent, just beef up your battery bank instead and do the alternator later when you got the funds, but right now you need a system to get bumping so might as well start off in the right place instead of having low budget and buying garbage amps kuz of it.
As for a box, hit up boomsday, one of the members on here, he'll hook you up with a quality custom box shipped to your door for hella cheap.