Amazon offers the Polk Audio PSW10 10-Inch Powered Subwoofer for $90 with free shipping. Retail price was $240.
- Single 10-inch subwoofer in black with built-in high-current amplifier for big bass
- Equipped with one 10-inch polymer-composite dynamic-balance cone driver
- Laser-based Klippel measurement technology for improved linearity and deep, precise sound
- Non-resonant all-MDF enclosure construction with 0.75-inch-thick baffles and internal bracing. Amplifier Continuous Power – 50 watts.Amplifier Dynamic Power – 100 watts
- Measures 14 by 14.38 by 16.12 inches (WxHxD)
- Polk Audio loudspeakers and subwoofers are capable of playing at extremely high volume levels. You should limit prolonged exposure to volumes that exceed 85 decibels(dB).