If you haven't heard of a 10" driver being able to reproduce 20Hz FR, chances are you haven't listened to a PB10-ISD...
I'd have to agree regarding the use of this to fill the size room noted, it may come up a bit short. If you can bump your budget up a smidge, you may want to consider one of the 25-31 or 20-39 PCi cylinders from SVS. While this isn't going to crumble your place in around you, it will likely give you some solid bass response and allow you to keep your budget somewhat reasonable. The STF-2 and ULW-10 are also good performers in this price range, but the SVS cylinders would fill that room out nicely whereas these might come up a bit short similar to the PB10... -TD