Time Setters produces several models of clocks. An outside supplier has offered to produce the commercial clocks for Time Setters for $350 each. Time Setters needs 500 clocks annually. Time Setters has provided the following unit costs for its commercial clocks: Direct materials $ 70 Direct labour 80 Variable overhead 75 Fixed overhead (30% avoidable) 120 Prepare an incremental analysis which shows the effect of the make or buy decision