Notson, Inc. produces several models of clocks. An outside supplier has offered to produce the commercial clocks for Notson for $420 each. Notson needs 1,200 clocks annually. Notson has provided the following unit costs for its commercial clocks: Direct materials $100 Direct labor 140 Variable overhead 80 Fixed overhead (40% avoidable) 150. Prepare an incremental analysis which shows the effect of the make-or-buy decision.