The relevant cost to make the cookies per cookie is the cost that Fancy Cookies incurs if it decides to make the cookies. This includes the direct materials cost of $1 per cookie, the direct labor cost of $2 per cookie, the plastic wrap packaging cost of $0.10 per cookie, and the fixed kitchen costs of $600/200 = $3 per cookie.
Therefore, the relevant cost to make the cookies per cookie is $1 + $2 + $0.10 + $3 = $6.10. Rounded to two decimal places, the relevant cost is $6.10 per cookie.