Cullumber Corporation currently manufactures 2,600 staplers annually for its main product. The costs per stapler are as follows: Direct materials $7 Direct labor 11 Variable overhead 8 Fixed overhead 11 Total $37 Gallup Company has contacted Cullumber with an offer to sell it 2,600 staplers for $30 each. $ 9 of the fixed overhead per unit is unavoidable. Prepare an incremental analysis for the make-or-buy decision. (Enter negative amounts using either a negative sign preceding the number e.g.-45 or parentheses e.g. (45).) $ > $