Question about servo motors

first of all, I'm a newbie and I need lots of help. I found these
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1787258271&rd=1
motors on ebay. is $480 a good deal for 3 servos with a peak torque
of 600 oz.in.? If not, where can I find a better deal? Will these
motors have sufficient torque to convert a dovetail mill/drill to CNC
without replacing the acme leadscrews with ballscrews?

also, would the gecko g320 be sufficient to run these? What are some
advantages of the g340 over the g320? What type of power supply
would I need to run these with the gecko g320 or 340?

I'm still pretty unclear as to exactly what I need as far as the
electronics go to control the CNC. Any help would be appreciated.
--Bryan