Monoprice, a website generally associated with peddling A/V cables on the cheap, also makes audio components on the cheap. And in a space where audio gear costs as much as houses, cheap speakers are normally ignored. But Monoprice's subwoofer may be the exception.
Cnet's Steve Guttenberg says that Monoprice's line of subs are wholly respectable, especially given the sub-$100 pricetags: $57 will net you an 8-inch, 60-watt sub, while $84 will get you a 12-inch, 150-watt boomer. Overall, Guttenberg preferred the smaller sub as it had good bass definition, even if lacking in power (it only goes down to 50Hz). The bigger sub, in his words, sounded sloppy, but had decent power. But all in all, they provide a cheaper alternative to systems upwards of $300. [Monoprice via Cnet]