We have a "problem" at our hackerspace where lots of people want to control the stereo. Usually there are 5-10 people in there working, there is always music playing, and the person controlling the music (or the "wubs" as they are affectionately called now) changes pretty frequently.
We should be exactly the target market for the Q.
Except we already solved this problem. We bought a really long cable off of monoprice, and we bought a bluetooth audio receiver. They both plug into a mixing board, and they allow everybody to play music. Switching between who "has wubs" involves going "hey, you want wubs?".
It works really well, it almost never breaks down, it doesn't require anybody to install anything on their phones, computers, cassette players, arduino shields, theramins, contact microphones, or whatever else we decide we want to play over the PA.
Most importantly, it doesn't cost $300.
...and then one of us bought one and brought it into the lab.
Here is what happened: http://yfrog.com/z/oe42wqagj