The county board of education may subscribe for membership in, or otherwise become a member of, any state or local organization of governing boards of school districts or members thereof, or of county boards of education or members thereof, or both, which has for its primary purpose the promotion and advancement of public education through research and investigation, and the cooperation with persons and associations whose interests and purposes are the betterment of the educational opportunities of the children of the state. The costs incurred for the purposes of this section shall be payable out of the county general fund.