2e0poz,

You don't say what size it is your looking for, but as I understand it a servo is just a motor with some form of position/speed device attached to the end for feedback, in my case I just used an ordenary model boat motor for the cutting of PCB's driven by an old battery charger I had lying around. Eventually it will have a PWM speed control device to manage the rpm's and I already have the parts lying around for that and the circuit designed, just needs the pcb cutting.
The chuck body I turned out of round ally stock stuck 3 bearings inside it and turned some round steel bar to fit the bearings with a 1/8" hole in the end, thing is it worked, much to my supprise, although I have no need to take big cuts it did surface the ally table just fine with a 1/4" bit in it. If your asking about the electronic's side I build my own using the circuits on the internet, and there are many to choose from, but the last thing I would do is link it up to the pc.

Hope this helps
Mark