(1) No commissioner nor any person for his or her benefit shall purchase or be directly or indirectly interested in the purchase of any of the premises sold.
(2) No guardian of any minor or person of unsound mind party to the proceedings shall purchase or be interested in the purchase of any of the lands the subject of the proceedings except for the benefit or in behalf of his or her ward.
(3) All sales contrary to the provisions of this section shall be void.