Okay, I've never used Dayton Audio, so I can't attest to its quality, BUT slickdeals is showing a deal from Parts Express that has the SUB-1000 powered usbwoofer for $109.10 after promo code, with free shipping:
https://slickdeals.net/f/16262905-dayton-audio-sub-1000-10-100-watt-powered-subwoofer-109-1