I have a set of pre-recorded sound samples that I am using. The way I see it, there is a difference between a controller and and a "stand alone" instrument. Using protocols such as MIDI and OSC, data can be sent out of a controller which will leave the actual playing of the sounds to another device (computer, sound module etc.). Conversely, the sound generation could be done using on-board electronics and all a user has to do is connect an audio jack to speakers. It is like the difference between a MIDI controller and a regular electronic keyboard. Of course, you can do both in one instrument.
I am looking for a low cost way of doing an electronic instrument where you can just plug in speakers. For example, I found the Rugged Audio Shield (http://ruggedcircuits.com/html/rugged_audio_shield.html), but unfortunately there aren't any available at the moment. So I am trying to find other options that will do the job.