Brands I'd look for would be the same we generally recommend around here....SVS, Hsu, Power Sound Audio, Rythmik, RSL, Monolith, JTR, etc. Mostly I'd avoid Klipsch, Definitive Technology and Polk (some of the poor reputation of ported subs can be traced to some of these brands' subs, too). I like shadyj's suggestions (he's our sub/speaker reviewer, fyi). You could look for a while for a used one to come up, too, they don't come up all that often, especially within your budget. Might be easier if you just mention where you're looking or some subs you spotted for consideration. Wattage doesn't mean a lot, hopefully the sub designer provided for adequate amplification for the particular driver/box.