a. Make or Buy Terry Inc. manufactures machine parts for aircraft engines. CEO Bucky Walters is considering an offer from a subcontractor to provide 2,300 units of product OP89 for $110,400. If Terry does not purchase these parts from the subcontractor, it must continue to produce them in-house with these costs: Costs per Unit Direct materials Direct labor Variable overhead Allocated fixed overhead $25 14 12 Required Calculate the relevant cost for producing the product. Relevant Cost Per Unit Total Calculate the additional cost or savings of producing the product internally versus purchasing the product externally, from a supplier.. Additional cost of producing internally