Lab jacks cost between about $30 and several hundred dollars. Use the OpenSCAD files to customize it for your application, print on your favorite open source 3-D printer and enjoy for a few bucks.
This works well and can get a good quality z-axis small change for any standard optical arrangement. However, the gearing is a bit sticky so will need improved if you are going to automate with lots of precise height changes.
Full information here on appropedia
Thanks to Nick for the designs and GregFrost for the gears.
This component is part of the Open-source Optics Library: Zhang C, Anzalone NC, Faria RP, Pearce JM (2013) Open-Source 3D-Printable Optics Equipment. PLoS ONE 8(3): e59840.
This is part of a larger project to reduce the cost of scientific equipment using open-source hardware. Read more here