At the moment I outsource a cnc contract to another company for a customer I deal with I intend to to take it in house but it's low volume custom parts. It will be very profitable to me if I CNC the parts myself but only because rarely do we make more than 2 of the same item.

My experience has been that setting up costs are high vs production costs so if I was to make 100 of the same item it becomes more profitable to outsource but 10 I should probably do it myself.

Outsourcing has both advantages and disadvantages and not everything is cost, Accuracy, quality of finish, reliability and just sometimes needing to get a rush job done are factors that need to be considered on a job by job basis.