after a bit of googling around i found this:
https://sourceforge.net/projects/arduinoascomfocuser/
after a quick look on ebay and jaycar to price things, the total cost came in at $50 so i couldnt really resist.
if it does what it says it does (and im sure it does) thats pretty amazing as far as bang for buck goes.
of course my grand idea has to be on the saturday of a long weekend.. but i'll update when i get the bits and start to get something together.