I'd stay away from anything with Jensen on it. you can get some pretty decent used Fosgate or Memphis Subs fairly inexpensive (couple hundred bucks or so). As Subwoofer said, above, a sub box isn't just a box with a hole in it, first you gotta decide whether you want a ported or sealed enclosure, there is a difference..... second, each sub has air space requirements that must be met in order for your subs to perform properly. Doesn't sound like you are getting into any competitions, so we'll leave out the resonant frequency bit..... but there is a lot of math involved in building a box properly, but i recommend building one, and not buying one.