Hey Seth, glad you gave us the chance to save you from a horrible fate. Short answer: none of the above. If I were looking for a cheap sub, I'd get either the
NXG NX-BAS-500 (unfavorable reviews on NewEgg notwithstanding, it's likely to be
an excellent bargain) or the
Dayton SUB-1500 or
SUB-1200. Indeed, since the SUB-1200 is on sale, you could almost get two of those for what you would've paid for the JBL. Having a pair of subs is nice for evening out room response, making it easier to flatten the dips and peaks across a wider seating area. Again, if I were in your position, I'd give the NXG an audition first though.
Of course, all this is tentative. If you're trying to fill a large room (over 2500 cubic feet or so), you ought to consider increasing your budget and aiming for something a little more grown up.