Provo Provolone Company is a purveyor of fine provolone cheese. Provo is considering adding a line of cheddar cheese, in addition to selling provolone. After conducting a differential analysis, Provo finds that the variable cost of producing 1,000 pounds of cheddar is $3,000 and the differential revenue would be $3,500, giving Provo $500 in additional profit. What is the type of cost Provo will incur if it produces cheddar cheese instead of Muenster?