Each member of the Board of Registrars of Blount County, upon approval by the Blount County Commission, shall be entitled to receive an additional expense allowance of twenty dollars ($20) per day to be paid as prescribed by general law for the payment of other compensation and expenses of the members of the board of registrars. The portion of the compensation of the board of registrars which is not paid by the state shall be paid from the county general fund.