$35/each. Arlington TVBU505-1 Recessed TV Box Wall Plate Kit Paintable 2-Gang,
White. I have 3 of these, brand new in the wrapper.
Arlington’s recessed non-metallic combination power and low voltage TV BOX Kit
includes all you need to mount a flat screen TV secure, and flush against a
wall.
The box offers power in one side and low voltage in the other for Class 2
wiring of satellite or cable TV, speakers and more.
http://www.aifittings.com/catalog/home-theater-audio-video/multiple-gang-recessed-tv-box-for-power-and-low-voltage/TVBU505
