I'm sure dnewma04 will stroll on by this forum. Until then, I am sure he and others would like to know a few things before offering much advice.
What is the budget for the driver and/or amp if you don't have one?
What is you intended crossover frequency?
Are you using a receiver with dedicated subwoofer pre-out (like any of the Dolby Digital ones)?
What do you plan to use to power it?
What size of a cabinet is acceptable?
What mix of music to movies will it be used for, like 50%/50%? Only music?
Ever built a ported box before?
Here are a couple things to recommend without any of the above info. First, stay far away from car audio drivers in the home. Most car audio drivers that do sound good are a) expensize becuase of the brand on the cone and b) inferior to home drivers because they rely on a lot of cabin gain to get a good response. Second, if your amp can handle it, get lower impedance like 4-ohm or 2-ohm. You'll get more power out of your amp. That leads to three - the more power the better with bass. Lower frequencies require a lot more power to produce the same sound level (loudness) than higher frequencies.
There are some excellent deals on home audio drivers all the time. The
Lambda Acoustics line is tops in value until the end of March.
Last for now - I'm sure Dave and others can help you get the best sound and output for your money. Dave helped me with my twin 15" subs and I later got a nice amp to give each one 500 watts. I love it!
Aaron