All election notices, department reports, ordinances, charters or charter amendments, advertising, publicity of affairs or other publications required or authorized by this Charter, or by any ordinance of the city, to be made in any newspaper, and all such publications for which the City of Fort Worth may be liable, shall be paid for by the city at such rates as shall not in any event exceed the ordinary and regular advertising rates charged other advertisers. No bill shall be paid by the city for such advertising or printing in excess of the lowest prevailing business rates.