Rashi on Leviticus 27:12/רש"י על ויקרא כ״ז:י״ב

1כערכך הכהן כן יהיה AS THE PRIEST VALUES IT, SO SHALL IT BE for any other person who comes to buy it from the Temple treasury (in contrast to the owner himself who, if he redeems it, must add a fifth to the valuation, as stated in the next verse).