Honestly, there aren't any good subs in the "sub" $100 price point. A sub isn't just about how much output it has. It's also about tightness, quickness, extension, and efficiency. May I suggest saving a little and getting something a little better? I'm not suggesting a huge sub for you, especially if it's a small space you are trying to fill, but if you are willing to up that budget just a little bit, I think you'll be much happier in the long run.