I bought all my stuff out on eBay. They have just about everything. Do your research on Crutchfield.com and then check out eBay to save some $dough$. Some killer deals if you are patient.
As far as the gear it all looks pretty good to me. I decided on an Alpine MRD-M300 for the subs. Hits like a champ. www.sounddomain.com
is where I bought all the knick knacks, power cable etc.
Oh, solder everything and then heat shrink! Better connections, looks better, etc.