I think he said those are 12's on an earlier post. I was planning on using 10's but the 12's fit pretty well.
As far as house speakers, I think that they are a bit different. Check the specs on the back of the cabinets. Impedance and all that jazz. I think it relates to the resistance native to the speakers. Most car amps and home amps are different if I remember correctly, though car amps are pretty versatile. Not really my area though.
You can get a pair of 12" car subs at best buy for under 200 bucks, plus box, amp, labor, wiring. A nice pair of subs like Lok's will cost quite a bit more. I've used cheapies a few times and they sounded fine.
You can get aluminum cones, which I think would look quite sweet in the bullitt...