Hi Ed,

I've been using MoI for many of my jewellery designs & output them as STL files for milling.
My mill is a Roland MDX-15 which I've fitted with the rotary unit made by Fourth Axis.
http://www.rolanddg.com/index.html
http://fourth-axis.com/

The CAM software is supplied by Roland as part of their package which uses their own machine code.

There seems to be many 3 axis CAM programs that are fairly cheap, Vectric's Cut3D or Delcam's MillWizard being a couple of them.
http://www.vectric.com/
http://www.millwizard.com/default.asp

But as far as I'm know, once you've moved into 4 axis CAM, there's nothing "cheap".
It seems the starting price for most of them is about $4000 & up!

regards Colin