Section 103. A city which accepts this section in the manner provided in the following section or has accepted corresponding provisions of earlier laws, or a town which accepts this section or has accepted corresponding provisions of earlier laws, may establish a purchasing department, to consist of a purchasing agent and such assistants as the city council or selectmen may determine. In cities the salaries of the purchasing agent and assistants shall be determined by the city council. In cities the agent and assistants shall be appointed by the mayor for such terms of office as may be prescribed by ordinance, and in towns they shall be appointed and may be removed by the selectmen. The purchasing agent shall purchase all supplies for the city or town and for every department thereof except in case of emergency. All purchases or contracts for purchases exceeding one thousand dollars in amount shall be based upon competition. A record shall be kept by the department of the prices paid for the supplies, and shall be open to the inspection of any citizen.