FM Transmitter with voice recorder.
It's a short range FM Transmitter that has a built in voice recorder for up to 4 minutes made.
The recorder would have a simple button that you would press to record with a built-in mic and small speaker for playback. The recording when transmitting would loop forever.
The unit would be powered by a small battery and solar panel or just solar panel if that would work both indoors and out. The unit would only have to transmit during daytime hours.
I would need the FM Transmitter to transmit no more than 100 feet and to meet FCC for USA. The transmission would need to be a very clear transmission because it is going to be used for advertising. It does not need to be in stereo.
I've attached an image of what I would like to have made and the case is available at http://www.polycase.com/