If you're feeling the DIY itch at all, you could certainly pull off something pretty sweet with a
Minnowboard. It is basically an Intel Atom-based "tiny computer", something like a Raspberry Pi, but not ARM, and it is an open platform. One of those, a nice Compact Flash or SD card to run it off of (or a mSATA SSD if you're flush with cash), Linux, MC...
You'd have to find a case to jam it into, and it costs a lot more than a Raspberry Pi, but it is also a full-fledged PC that is hundreds of times (if not 1000s) more powerful than the Raspberry Pi and other similar ARM boxes. Like I said, though... It is also an order of magnitude more expensive than what you were looking at.
I think you could also run a Raspberry Pi with Android and put Gizmo on it, but you'd need a way to control it as you can't (maybe yet) push from MC itself to Gizmo. You could almost certainly figure out a way to make a Raspberry Pi into a DLNA Renderer though, and that should work.