Each commissioner shall serve without pay but the council may allow the secretary such compensation, not exceeding $100 per year, as it shall deem commensurate with the additional services rendered. The council shall pay from the municipal treasury all expenses incurred by the commission in connection with the performance of its duties and shall furnish it with all supplies, stationery, and equipment it may require, but all bills and accounts shall be audited and approved by the president and secretary of the commission before being paid by the council.