Let the hive mind of Engadget get that for you.
"I am looking for a device that will stream sound from one source to several recipients. For example, I want to stream sound from my TV or stereo to my phone or MP3 player that has radio and Bluetooth capabilities. I have looked into radio transmitters and they seem like a decent choice, but I can't find one that uses external power (USB or from the plug) and I would want one with a transmit range of around 50 meters. Thanks!"
On the cheap? It's nearly $700! I'm all for building my own gadgets, but projectors have come down in price a lot in the past several years. For less than $700 you can get something likely to surpass this in every way, not to mention it will be far more compact.
The only way it would make sense to build something like this is if you already had an extra LCD monitor gathering dust.