You may not need a cnc mill to just drill and tap holes.
For a machine control Acorn, it one of the better controls that can do rigid tapping, Mach3 is still good for anything to do with milling, not so good in the rigid tapping area though.
Need to know if you need to do any milling on the parts??
A flex arm can be better for taping production run pieces like this, it can be mounted onto a work bench, and you would use fixtures for your parts.