Signa Corporation currently manufactures 3,000 staplers annually for its main product. The costs per stapler are as follows: Direct materials Direct labor Variable overhead Fixed overhead Total $3.00 8 4 7 $22.00 Darsel Company has contacted Signa with an offer to sell it 3,000 staplers for $18.00 each. $5 of the fixed overhead per unit is unavoidable. Prepare an incremental analysis for the make or buy decision