The City Council may provide the funds, equipment and accommodations necessary for the work of the Commission, but the expenditures of the Commission, exclusive of gifts, shall be within the amounts appropriated for that purpose by the City Council of Trustees and no expenditures, nor agreements for expenditures, shall be valid or legal in excess of such amount; provided, however, that, such Commission shall have the authority and the power to accept and receive donations of cash or property, gifts, bequests and grants and, with the approval of the City Council, may use such non-appropriated assets as the Commission shall deem beneficial and advantageous to the city.