I bought 2 JL 12WO (12") subs, cost me $340 for the pair, and a JL e2150 amp for $350. The subs are rated low (125wrms each), and so is the amp (40x2 wrms), but overall it cranks hard as f**k!!
JL Audio are bloody fantastic, I would definetely recommend them to anyone!!
I haven't had my stezza tested or anythin, but it's set of car alarms b4, and when I go passed Repco my bro (he works there) rekons it shakes the wall so much that everything on it is vibrating HAHA!!
And the best bit of all.....it shits all over a lot of stereo's which costed a lot more then mine
About the box, well I paid about $30 for some MDF, about another $15-$20 to get it all precut, then I chucked it 2gether myself. I made it to the subs specs to, which is a downside when u buy boxes already made.
The gear I bought was bottom of the range stuff, but it cranks hard. JL don't make the 12WO's anymore, they have replaced it with another model...they're now white....but I doubt the price would be much more then the 12WO's.