I'd be interested in a sound board. You including all the buttons and speaker too?
I will be including 2 wireless transmitters with one of them wired extended push buttons so you can put the transmitter in a rifle or gauntlet or wherever you can get to it with your fingers. Once I am more mobile I am going to start working on the button extensions.
As far as the speaker, I may include a small 3 watt speaker, but the board is going to have a 3.5mm headphone jack for plugging it into an aker type amplifier system.
This kit is going to take a while to develop since I will be integrating a bunch of different functions, but once I have a prototype, I will post up here.