- Parks Corporation currently manufactures 3,000 staplers annually for its main product. The costs per stapler are as follows: Direct materials $ 3.00 Direct labor 7.00 Variable overhead 4.00 Fixed overhead Total $21.00 7.00 Gallup Company has contacted Parks with an offer to sell it 3,000 staplers for $18.00 each. $5 of the fixed overhead per unit is unavoidable. Instructions Prepare an incremental analysis for the make-or-buy decision