If the number of years after the jubilee is more, increase the selling price. If the number of years after the jubilee is few, decrease its selling price, because he's selling to you according to the potential production volume of the land.

"He is to bring an accounting to the one who bought him, starting from the year he had sold himself until the year of jubilee. The price of his sale is to correspond to the number of years comparable to the time a hired servant stays with him.