[CAD_CAM_EDM_DRO] CNC conversion, what does it really cost??

After looking at more than a few web sites and getting more and more
confused as to what I really need I'd like to get a ballpark figure from
someone that's been-there-done-that.

The machine is question is a Shoptask 3-in-1, as stated in a
previous message, I'm getting ball screws next week (I'll have to
machine/modify them myself for my tool)

So the next step is motor selection and drives and power supplies
and software I gather?
I already use Pro/E for my design/drafting, but I know I'll need
software to read or convert the files to G-code.

As with most on this list, I'd like to stay within a certain price
range. Could I put together something for $600-$1000 for 3 axis?
I already have an extra Pentium based computer so that part should
be covered.

Thanks,

Mike Mueller