Sparkfun announces Actobotics, a full line of gears, motors, mounts and more! There is just about every size of gear, tube, or shaft that you need.
Additionally, instead of plastic, they opt for aluminum or stainless
steel, and use ball bearings instead of relying on plastic bushings.
Lastly, we really like the fact that nearly all of the products work
seamlessly with one another. Actobotics products use either a 0.77" or
1.5" hole pattern, allowing you to easily connect a gear to your servo,
and then connect your servo to one of the channels or beams.
https://www.sparkfun.com/news/1345