DM = 9 DL = 5 Variable overhead = 1 DEPRECIATION = 3 SUPERVISOR'S SALARY 2 GENERAL FACTORY OH 10 UNIT PRODUCT COST $30 The Make or Buy Decision 1 The special equipment used to manufacture part 4A has no resale value. The total amount of general factory overhead, which is allocated on the basis of direct labour hours, would be unaffected by this decision. The $30 unit product cost is based on 20,000 parts produced each year. An outside supplier has offered to provide the 20,000 parts at a cost of $25 per part