(a)(1) Except as provided in subsection (b) of this Code section, it shall be unlawful for any part-time public official who has state-wide powers, for himself or on behalf of any business, or for any business in which such public official or member of his family has a substantial interest to transact any business with any agency.

(2) Except as provided in subsection (b) of this Code section, it shall be unlawful for any part-time employee, for himself or on behalf of any business, or for any business in which such employee or member of his family has a substantial interest to transact any business with the agency by which such employee is employed.

(b) The provisions of subsection (a) of this Code section shall not apply to:

(1) Any transaction made pursuant to sealed competitive bids;

(2) Any transaction when the amount of a single transaction does not exceed $250.00 and when the aggregate of all such transactions does not exceed $9,000.00 per calendar year;

(3) Any transaction involving the lease of real property to or from any agency if such transaction has been approved by the State Properties Commission or the Space Management Division of the Department of Administrative Services; and

(4) Any transaction involving the purchase of surplus state property at a public auction.

(c) Any person who knowingly violates subsection (a) of this Code section shall be subject to the penalties provided for in Code Section 45-10-28.