Regarding musical box custom tunes, I have been getting a lot of
inquiries about simple custom tune one-off movements.  Although
I prefer to put custom tunes on my own six-octave historic reproduction
boxes, it seems that many people are really only interested in a simple
20-second melody.  In that case I use a commercial movement of 18, 21
or 30 teeth as needed.

I make a new cylinder with the new musical program and retune the
existing comb as needed.  For such a small comb the arrangement is
typically very simple.  If there are no significant copyright expenses,
the result costs a few hundred dollars rather than a few thousand
dollars.

Jonathan Herz
http://www.herzmusicbox.com/