Target offers the Vizio SmartCast 40" 5.1-Channel Wireless Sound Bar with Subwoofer, model no. SB4051-D5, for $299.99. In cart, the price falls to $254.99. (Amazon charges the same.) With free shipping, that's the lowest total price we could find by $25. It features a 35Hz to 20kHz system frequency response, two satellite speakers, 6.5" wireless subwoofer, 802.11n wireless, Bluetooth 4.0, built-in Google Cast, compatibility with the Vizio SmartCast app (which allows you to control the soundbar via your mobile device), remote control, HDMI, USB, and auxiliary 3.5mm port.
Update: Amazon now offers it for $249 with free shipping.