Subject to approval of the Board, which shall take into account the primary responsibility of the Secretary towards the classified service, the Secretary may enter into agreements with any agency excluded from this chapter, or with any municipality or other political subdivision of this State to furnish services and facilities of the Board to such agency, municipality or political subdivision in the administration of its personnel according to merit principles. Any such agreement shall provide for the reimbursement to the State of the reasonable cost of the services and facilities furnished, as determined by the Secretary. All excluded agencies and all municipalities and political subdivisions of the State are authorized to enter into such agreements.