CNC a Mill/Drill?

I am interested in any suggestions on converting a
mill such as the ENCO RF31 Mill/Drill to CNC. I am
a newbie to CNC. My understanding so far is that the
leadscrews need to be replaced with ballscrews. Servos
fitted. Drivers needed. (Geckos seem very popular.)
I would use the EMC from NIST.

I would like to end up with something more than a
useless toy but have to watch budget. At the last
WESTECH I saw a knee mill by KENT with a Mitutoyo
control for $13K. Too steep for me but I would like
to get something as close as I can for about half
the sheckels. I am afraid to got the used machinery
route because I just do not known enough about what
I am doing.

I would be very grateful for your thoughts.

Thanks for the read.

Barry