I think that everyone had a nice input on your budget and system.
JL Audio is amazing, and I've heard much about the XXX and Brahma, but the only downside is that you won't be able to hear it for yourself like you could a JL sub at a store. You should go out and HEAR for yourself what you like. RE and Adire aren't the only good brands out there, they just happen to be cheap. It's a risk if you purchase buying something without hearing it. It's like a blind date, all your friends tell you a girl is hot, much like how RE and Adire are the "BEST", and then you may find yourself not into this "hot girl" (or in this case, the subs).
Also, for your information, I own a 1997 Nissan Extended Cab Pickup truck. This is my setup, and it is PURELY amazing. SQL is what I wanted, and SQL is what I got. I push 600 watts to each w7, which is underpowered, but it's still amazing. When I get more money, I'm getting another JBL amp to give them each 1200 watts.
Headunit: Pioneer Deh-840MP
Subs: (2) JL 12W7's
Sub Amp: JBL 1200.1 (I'm adding another VERY soon)
Comps: Image Dynamics Chameleons 6.5's
Comp Amp: Pioneer GM-X364 (Also to be replaced...its giving 150x2)
Wiring: Stinger 4 gauge
Other: Optima Battery, Magic 3
This setup is great I think. Working with limited space as yourself, and having a budget can be tough. Go listen to some stuff and see what you like/dislike about different subs. JL Audio is great, and I will recommend it on my behalf.
Good luck with the bumpin'