Hi tarasan
First get a number of quotes to determine if Koike are giving you a good deal. In the end the machine is just a skeleton to convert to CNC. You don't have to use Koike just because they made the machine. Since this is a company machine you need to do some cost justifications to work out what potential savings you can make by CNCing it vs. the steep learning curve to be able to DIY.
If your machine is like what I think it is (we had an optical tracing doo-dad on a flame cutter at a company I used to work for) all you need is to tender the manufacture of a control box that can be driven by Mach or some other PC based controller. Basically all you need to do is to spec the current motors and encoders (or buy new) so appropriate drives are selected. A clued up industrial sparky could build it for you and I wouldn't mind betting there would be a few guys in these forums who have built a control box for a plasma/flame cutter who would be willing to share their experiences with you and maybe even give you some specs on how they built theirs.
Cheers
Derek
<insert witty comment here>
derekj308