Rakuten.com has the 12" Monoprice Monolith 500W Powered Subwoofer (Black) on sale for $659.99 with coupon code MN100 and free shipping.

• THX Ultra Certified - for large sized rooms, up to 3,000 cubic feet in size, with a 10-12 foot viewing distance from the screen
• 12" Woofer
• 500 Watt Amplifier