I just purchased the PB12-Plus from SVS. The thing is simply awesome. I don't know much at all about the numbers and all that jazz that people like to quote with subs. All I can say is that the bass sounds to me like I would want bass to sound. It hits when it's suppose to, and it fills the background when it needs to. I listened to a lot of HT systems and I think the bass was where most people struggled. Either it was too much, i.e. couldn't hear voices, only deep noises. Or, the systems were loud without bass. To me, loud and bass are not the same.
Unfortunately the PB12-plus is a little out of the price range you quoted. And, I'm not saying that it's the sub for you. I will say that SVS was super easy to work with and I am COMPLETELY satisfied with their products. I would call them or email them and see what they have to say. I don't think you can go wrong with their stuff.