1. It shall be the duty of the commissioners of the county commission in all counties of the second class, and in all counties of the first class not having a charter form of government, if there is no purchasing agent appointed pursuant to section 50.753, on or before the first day of February of each year, to estimate the kind and quantity of supplies, including any advertising or printing which the county may be required to do, required by law to be paid for out of the county funds, which will be necessary for the use of the several officers of such county for the following year, and to advertise for sealed bids and contract with the lowest and best bidder for such supplies. Before letting any such contract or contracts the commission shall cause notice that it will receive sealed bids for such supplies to be given by advertisement in some newspaper of general circulation published in the county, such notice to be published once per week for three consecutive weeks, the last insertion of which shall not be less than ten days before the date in said advertisement fixed for the letting of such contract or contracts, which shall be let on the first Monday in March, or on such other day and date as the commission may fix between the first Monday of March and the first Saturday after the second Monday in March next following the publication of such notice; except that if by the nature or quantity of any article or thing needed for any county officer in any county of this state to which sections 50.760 to 50.790 apply, the same may not be included in such contract at a saving to such county, then such article or thing may be purchased for such officer upon an order of the county commission first being made and entered as provided in sections 50.760 to 50.790; and except further, that if any supplies not included in such contract are required by any such officer or if the supplies included in such contract are exhausted then such article or thing may be purchased for such officer upon order of the county commission first being made and entered of record as provided in sections 50.760 to 50.790.

2. The county commission may authorize the purchase of supplies, not including for contractual services, at any public auction held.

3. No contract for a purchase under this section shall arise until the commission has approved a purchase order for the supplies for which the bids were advertised and submitted under this section.