The main thing to keep in mind is that if anything, MIDI files will be even more work than the more realistic sounding sampled stuff we work on with all the great tools. That means, you must try not to charge less than you would for anything else. Just because it won\'t sound as huge as streaming music, doesn\'t mean that you must charge less. So, go by what you would charge for music in any other situation. Perhaps charge by the completed minute of music.