If you want something pre-made and easy, Pioneer makes a compact 10' sub that I've put in my truck:
It's durable. I'm able to load up the Access Cab with stuff, put crap on it, and it just sounds great. Looks inconspicuous too:
Went to Kreative Audio on 5th Avenue for an amp install, but they took an hour and a half longer than estimated to put in 1 amp. Then they tried to tell me that my cheap stock speakers are fine (the magnet was barely bigger than a quarter). They wanted to make special enclosures for my stock, $3 speakers. Which would lead me to buying more speakers very shortly. I didn't go back to them.
Went to Safe and Sound for my next install of MB Quart speakers, another amp, sub, and window tinting. They were alright guys there. BUT - I found out later that tint on the driver and passenger windows is illegal. I'm thinking of getting it scraped off now.
I can let you hear it at the next meet-up on Dec 8th if you want to wait that long.