I imagine potentiometers can be had most anywhere, like Radioshack or Digikey. As for the micro linear servo. I know hobby shops that cater to RC planes and helicopters have most
any type of servo that the prop community will need.
Depending on what you put in Google will it might come up with different results. Like originally I was looking up "linear actuator" instead of "linear servo" and smallest at the time I saw was 20mm throw. Then used "Servo" and I find this 1.5G one with only 7.4mm throw.
http://www.amazon.com/Spektrum-1-5-Gram ... B001U3MHS4
Bleached out image doesn't show the moving portion, but I think that's designed just like the one from the youtube vid I posted. And only $20.
Trying to find a spec sheet. Want to know what it's operating and max voltages are. Not sure if a simple 9V will work or if it needs a full 12V or what.