The division shall have authority to purchase or lease communications facilities, services, or channels on terms which are for the best interests of the State of Nebraska. In making the decision as to what proposal is for the best interests of the state, the decision of the division shall be based upon, but not necessarily limited to, (1) the total cost to the state, computed in accordance with accepted governmental cost-accounting procedures taking into account taxes to be paid or foregone, interest rates, and obsolescence; (2) the quality of the service offered; (3) the comprehensiveness of the proposed facilities or plan; (4) the financial responsibility of the supplier or carrier submitting the proposal; (5) the repair and maintenance capabilities of the supplier or carrier; (6) the experience as a communications carrier or supplier, as applicable; and (7) the alternate methods or facilities available. The powers conferred by this section shall be subject to the condition that, except for existing state-owned facilities, the division shall obtain all telecommunications service as defined in section 86-121 from telecommunications carriers that are certificated or permitted by, or registered with, the Public Service Commission for any area in which such services are rendered. Any purchase or lease, except from such telecommunications carriers, made by the division shall be made through the materiel division of the Department of Administrative Services pursuant to the functions, powers, and duties of such division.