I currently have a kicker solobaric s12l7 in a ported box in my 2005 XLT powered by a kicker ZX400.1 (I know it's underpowered, I'm getting 1000 watts soon) and it is beyond loud. I payed just below $400 for the set up but it'll bump forever.
I like kicker a lot and would get either a comp or cvr subwoofer with a 400 watt amp. Kicker will give you your best bang for your buck but alpine, Rockford Fosgate, and pioneer are all quality.
I wouldn't get that west coast customs one, it is easy to setup but is also way overpriced and not worth it.
Search on ebay and half price car audio.com for refurbished stuff. It's brand new but way cheaper.
Hope I could help