The problem with "budget" subs is they tend to suck
They are tuned way too high so you get one note, droning "bass". Of these the Klipsch are some of the worst...and they aren't cheap.
Play some music on any woofer you listen to. Something with some acoustic bass is probably the most revealing.
I've taken a lot of heat for recommending Yamaha subs, but the SW315 is around $300 retail, Best Buy has the Athena AS400 for about that. Both Energy and Mirage have new 8" woofers for $350 retail or so. I'm sure there are some internet brands that don't suck, but I don't have any experience there, so I can't recommend them. These are the ones that seemed to be pretty good to my ears for not much money.
Check out a Sony SA-WX700
I know that Sony has never made a decent sounding sub before, but you have to hear a SA-WX700. Think you can audition one at Circuit City. Can buy one on the web for a little over $200.00 shipped.
250 watts with a sealed dual 10" woofer design. Goes pretty deep and believe it or not, sounds musical (not at all boomy) and blends well with most mains. Most of the people I've talked to that own one agree that they are a SERIOUS bang for the buck.