Shenzhen Geniatech Co. Ltd presents some interesting Android Powered Set-top-boxes. These could be sold for around $100 like the Apple TV or Roku box, but they just run the full Android OS including support for lots of video codecs. While Android is not yet really optimized for use on a TV with a remote control, this type of device will support the Google TV software (in this case, without HDMI pass-through overlay features) pretty soon once Google releases that software source code. As you can see on androidauthority.com, it has an AmLogic ARM Cortex-A9 800Mhz processor. Same ARM cortex-A9 platform as used by InnoDigital for their next generation WebTube product.
They are showing Samsung Hummingbird ARM Cortex-A8 model available now for $168 and showing their next generation running on ARM Cortex-A9 , they have a cool bunch of remote controls with Android buttons, shortcuts and even gyroscope based RF remote controller.
AmLogic 1.2Ghz ARM Cortex-A9, 8" 800x600 screen, could be an affordable such option.