Isn't the VTF-2 MK5 from HSU? I found it on their website, I assumed it was one of theirs but I've never actually bought a separate sub and looked at some reviews here and avs -- it seemed to be well received -- and that one was in the price range.
Regarding room size, just going off of body height and laying in weird positions (the best I can do until I can find my damn tape measure..) my bedroom is approximately 13x13
/Edit: It's worth mentioning that I only want to replace it because the sub I have is extremely old. All of my equipment is about 2 years old, and now a "brand new" receiver, but a 15~ y/o sub -- just some peace of mind while I have some expendable money instead of it dying at a time when I might not have the money to replace it immediately. Also, i'm assuming sub technology might have gotten a bit better in 15~ years as well.