thats a pretty big room to fill it with bass...you might have to up ur budget..or maybe consider two subs as with a larger room obtaining a linear bass response would be a challenge...unless you plan to sit in specific places only
Rythmik is known to make pretty good tight musical subs that also go pretty low performing well with movies
here is one...
http://www.rythmikaudio.com/FV15.html

Rythmik is known to make pretty good tight musical subs that also go pretty low performing well with movies
here is one...
http://www.rythmikaudio.com/FV15.html