Well, for starters I'm not an audiophile, because I don't even know what that means.
![Eek! :eek: :eek:](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
It doesn't take a classification to appreciate great sound though, from a novice to a true audio junkie.
I understand your dilemna, and share your pain on the 'needing money for the house, kids, other things'. The best I can suggest is do what I did, which was sit down with my wife and said, "Look, I want to put away a few bucks here and there to feed my HT habit, like maybe 'x' amount of dollars per paycheck, etc.'. We talked about it, and made sure our other priorities would be covered no matter what, and while it does take some time, it's not impossible. The good rule of life is that anything can be negotiated with fair compromise.
For a room that size, the x-sub may sound pretty good, but it won't provide any room-shaking effects at all. Throw in other unknown factors like vaulted ceilings (which you didn't specifiy) or an end that opens up into another room, etc., and it's much more difficult for that small sub to deliver powerful sound.
If you were able to save up the dough, get an SVS or Hsu model, I
guarantee you that you will wonder what the hell you were ever thinking trying to buy a sub for any less. It will wow you, trust me.
And your questions are anything but trivial.