I guess that makes sense.. lol thanks!
I would be looking at subwoofers from SVS:
http://www.svsound.com/products-sub.cfm
But their least expensive model is over your maximum limit.
What many people do is buy something with which they are not satisfied, due to having a limited budget, and they end up later on spending the money anyway as they want something better. And since selling off used gear typically causes one to lose money, in the end, they would have saved money if they had just waited and purchased something good in the first place, and they also typically would have the money for the better item sooner, as the money they spent on the cheaper item could have been the start of their saving for the better item. In general, good speakers (which includes subwoofers) are a good investment, as they make the most difference for how everything sounds, and they also do not need to be upgraded every time some new feature or audio format comes out. Receivers, on the other hand, are things that people often feel the need to replace, even though the old one works fine, but they just want some new features that were not previously available. That does not tend to happen with speakers so much.
I know this from experience, as I have wasted some money in the past, though not nearly as much as many people do with this hobby. Save your money for something really good, so you don't feel the need to replace it later on, and you will save money in the long run, and have the good thing sooner than you otherwise would have it.