amp ideas for my system

So, here's what I have, what I want and what I'd like to do... any and all ideas would be greatly appreciated. 1990 Ford Bronco II Alpine 9847 HU MB Quart 6.5" Comp (front) Factory 5x7 in the back I want a decent 4 channel amp that I'm going to install custom in the truck (lots of windows, so I have to get creative in hiding everything so nothing gets stolen). I'm planning on running the front speakers off the first 2 channels, bridging the second 2 to power one 10" sub, and leaving the back speakers running off the power from the HU itself. The reason for this is that my 1yo daughter sits back there and there's really no reason to have it louder/nicer/better/etc. I'm planning on installing the sub inside the side panel of the trunk, so it can't be a really deep sub. I'm trying to do all of this fairly inexpensivly, but I would like it to sound good. I'm a lot more interested in SQ than SPL, especially because of the baby. Any suggestions would be greatly appreciated, I can't make up my mind at all.

Oops, the MB Quarts are the QSD 216's

The following amps would be great, they are the OLD soundstream which means they are made good. Don't let the low watts fool you on these amps, they are WAY underrated. http:///.com/Soundstream-reference-644s_W0QQitemZ270008478938QQihZ017QQcategoryZ39737QQssPageNameZWDVWQQrdZ1QQcmdZViewItem http:///.com/soundstream-reference-604-car-amplifier-4-channel-used_W0QQitemZ230007862586QQihZ013QQcategoryZ18796QQssPageNameZWDVWQQrdZ1QQcmdZViewItem http:///.com/SOUNDSTREAM-REFERENCE-705S-AMP_W0QQitemZ160008690468QQihZ006QQcategoryZ4950QQssPageNameZWDVWQQrdZ1QQcmdZViewItem Sorry, cut and paste them in your browser. Can't cut and paste either, Go to e-bay and type in soundstream reference and any of the multi cahnnel amps are worth it.

focals new 4 channel. It uses a regulated power supply so no matter what your battery is pushin, the amp is always pumpin out the same amount. Plus its super clean power compared to most others out there. "People with mullets live 40% longer"   - Ricky Bobby

I couldn't find the focal amps online... can you point me in the right direction?

The thing is, I'm not neccessarily looking for total top of the line. I just want something that's decent, reasonably priced and puts out good sound. With my new family, I don't really have a lot of money to spend, nor do I want to spend a lot. I'd mostly just like to fill in the low end and add some more depth to my music. There's just so many different and competing brands out there, it's hard to know who makes a decent product, and who makes junk. Who makes a good 10" shallow sub? I'm going to modify the side panel in the inside of my cargo area and fab a box into it, but I don't have a lot of room. I want something that performs well, but it's very deep.