All work done under the provisions of sections 23-351 to 23-355 shall be done according to plans and specifications provided by the county board, and said board shall have authority to employ such persons as it deems necessary to prepare said plans and specifications. All work done under the provisions of said sections shall be by contract and said work shall be let to the lowest and best bidder after notice shall have been duly published for three successive weeks in a legal newspaper having general circulation in the county; Provided, where the estimate for labor and material is less than fifty dollars the county board may expend same without advertising. For the purpose of carrying out the provisions of said sections the county board may designate a committee of three residents of the county who shall serve without pay to assist in the location of said monuments or markers, the selection of sites, and the preparation of the record pertaining thereto. Said committee shall act in an advisory capacity to the county board.