Xia Co. currently buys a component part for $5 per unit. Xia believes that making the part would require $2.25 per unit of direct materials and $1.00 per unit of direct labor. Xia allocates overhead using a predetermined overhead rate of 200% of direct labor cost. Xia estimates an incremental overhead rate of $0.75 per unit to make the part. 1-a. What are the relevant costs for Xia to make or buy the part