Yet another subwoofer request Velodyne SPL-800

I'm putting together a surround system for my computer. I'm not sure why, but it seems like it would be fun and I had some equipment lying around, so why not? Some of you will cringe, but I'm using a Yamaha RX-v657 receiver. I know its not pro audio, but hey, this is a computer setup we're talking about.

In general, I'll listen to iTunes or play the odd video game in surround sound, but its become apparent to me that my Cambridge Soundworks 10" sub is just too sloppy. I'm using some Dynaudio 52 bookshelf speakers as my front stage so when I listen in stereo mode its obvious how bad the sub is.

I went out and listened to what I could and the Velodyne SPL-800 (which is the same as the MiniVee sans the eq gadget?!) seemed to fit the bill. I wouldn't call it musical but it was fast and filled the room like a 10" or even 12" woofer - surprising! I prefer the softer subwoofers that tend to blend but also have a bit of kick to them while still remaining transparent. I cant stand when a sub gets "thuddy" and localized - which is what my current sub does - I end up turning down the crossover to compensate for its lack of accuracy. So, I like the little velodyne, BUT, its out of my price range!

Can anyone recommend a less expensive subwoofer (I'm assuming I'll have to go used) that has a sound similar to the little Velodyne? Generally, I like when a sub is OVERPOWERED like the Velodyne (1000watts) so I'm particularly interested in suggestions that use this "overpowering" methodology. I have a budget of around $400, hopefully its not an unrealistic budget for mid/low-fi used gear.

I've searched here on the forums but I don't know what I'm looking at and am basically looking for people who have heard the Velodyne and can suggest a cheaper substitute.