Except as otherwise provided by law, no municipal officer, in a municipality having a population of ten thousand or more according to the last federal decennial census, shall be directly or indirectly interested in:
Provided, however, that the foregoing shall not be applicable if unanimously approved by the other members of the governing body of the political subdivision by a finding unanimously adopted by such other members and entered in the official minutes of the governing body, to be necessary for the reason that the services or property obtained are not otherwise available at equal cost.
N.D.C.C. § 40-13-05