yup.. i'm a noob to this kinda business.. and i need help finding the right sub for my setup. this is all in a 96 acura integra 4door (db7).

currently i am running:

pioneer head unit (deh-4800mp)
alpine vpower 1200 watt 4 channel amp to
JL audio 6x9 rears and JL audio 6" fronts
4gauge power wire into a distribution block (2x 15 amp fuses) exiting with 2x 4gauge power wire.
1 power wire powers my alpine amp, the other is for future sub and amp.
i already have RCA cables taken care of and wired to the trunk. 2 sets go to the alpine amp and 1 set is left out for future amp/sub.

what else am i going to need to run a nice sounding hard hitting sub? should i switch up to 0gauge power wire? (or at least to the dist. block.??) at what point am i going to need to wire in a capacitor? and how big of one will i need?

what are some general things i should know about in wiring this stuff up?

where is a good place to get a sweet deal on a 1000watt monoblock amp, typeR 10, and a box made for the alpine spec? would ebay have the best prices?

any advice would be much appreciated, and i thank anyone and everyone for their advice in advance.