As an interim move, how about printing a full sized template (paper?) to attach to the back plane and drill manually on a drill press)? The costs beyond that (learning/purchasing cam software, purchasing/learning how to operate the inc, etc.) will be substantial and may be difficult to amortize given your low production run count. Are there other production operations that might benefit from having a cnc?
As to the devices you may want to consider; mills are more appropriate for metal, but won't have as big a work envelope as a router. A router on the other hand won't have a spindle speed low enough for many metal working ops. A blending of the two may be needed (and possible).