(1) In order to obtain the services of ambulance service organizations, to obtain additional services from ambulance service organizations in times of emergency, or to obtain the services of emergency medical service organizations, a district may enter into a contract, for a period not to exceed three years, with one or more townships, municipal corporations, joint fire districts, nonprofit corporations, any other governmental unit that provides ambulance services or emergency medical services, or with private ambulance owners, regardless of whether such townships, municipal corporations, joint fire districts, nonprofit corporations, governmental unit, or private ambulance owners are located within or without this state, upon such terms as are agreed to, to furnish or receive services from ambulance or emergency medical service organizations or the interchange of services from ambulance or emergency medical service organizations within the several territories of the contracting subdivisions, if such contract is first authorized by all boards of trustees and legislative authorities concerned. The contract may provide for a fixed annual charge to be paid at the times agreed upon and stipulated in the contract, or for compensation based upon a stipulated price for each run, call, or emergency, or the elapsed time of service required in such run, call, or emergency, or any combination thereof.