The purpose of grants-in-aid shall be: (a) To encourage the development of local community initiative in broadening the scope of noninstitutional care and training programs for people with intellectual or other disabilities; (b) to maintain minimum standards in the operation of such programs; (c) to review the experiences of the individual community programs as they develop or maintain their programs; (d) to foster the progress of rehabilitation programs and half-way house programs to higher levels of quality and service. Grants-in-aid under the provisions of this act shall only supplement funds, shall not exceed 1/2 of the cost of operating expense of rehabilitation facilities or half-way houses for adults with intellectual or other disabilities and shall not be used for the purchase or construction of buildings.