Preston Wade Preston Wade, a local craftsman normally sells his handcrafted wooden birdhouses for $145 each. Preston has the capacity to produce as many as 60 birdhouses a week. In a normal week. Preston makes 20 birdhouses with the following costs per unit: Direct materials $12.00 Direct labor S15.00 Variable overhead $ 3.00 Fixed overhead S 5.00 23. Refer to the Preston Wade information above. Preston has received a special order from a local plant nursery to purchase 40 birdhouses for a price of $80 each. The nursery wishes to have the birdhouses engraved with their own logo, therefore, the order would require the rental of a special engraving tool at a cost of $250. if Preston accepts the special order. net income will increase by: a. $1,050 b. $1,750 c. $2,000 d. $3200