Post pics of the broken parts. if it is only the button you are lucky that you didn't actually crack the peghead (the end of the neck). Be sure to carefully look for cracks between the holes that the tuners go in. Those holes are major stress risers in the wood and it is a common area to crack if the guitar falls and hits the tuners.
Tomcunn, Djangostation.com in France did a run of SB tuner button repros, very good. In fact I've got one somewhere. Let me know if you're still looking. I believe he's planning to do another run soon also. But you can have mine if it's any use to you.
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viewtopic.php?f=9&t=7365&hilit=Button
If it is a metal part that is broken, that's going to be tough. Maybe someone experienced with machining for models could make new parts.