iv. any public authority, state agency, municipality, not-for-profit hospital organized under section forty-three hundred one of the insurance law, public library, or institution of higher education located in New York state shall be required only to pay the actual cost of providing for use of the fiber optic system, but not exceeding the fair market value determined pursuant to subparagraph (iii) of this paragraph. For purposes of this paragraph, "public authority" shall refer to entities defined in section two of the public authorities law. For purposes of this paragraph, "institution of higher education" shall refer to entities as defined in subdivisions two and three of section six hundred one of the education law. Disposals of the fiber optic system, or any part thereof, through agreements based on set fees shall not require the explanatory statements required by this section. Any disposal of property, contract for disposal of property or agreement made pursuant to this paragraph shall not be deemed valid and enforceable unless it shall first have been approved by both the comptroller and the attorney general.