The commissioner shall prescribe the fee necessary to cover the cost of state weighing, to be assessed and collected from the seller in the manner the commissioner may prescribe. The fee assessed must be the same, and the manner of collection of the fee must be uniform at all facilities. At any location where state weighing is performed in accordance with this chapter and the total annual fees collected are insufficient to pay the cost of the weighing, the annual deficit shall be assessed and collected in the manner the commissioner may prescribe. Additional money arising from the weighing of animals by the commissioner, which has been collected and retained by any person, shall be paid on demand to the commissioner. All money collected by the commissioner shall be deposited in the agricultural fund and credited to the livestock weighing account. Money in the account is appropriated to the commissioner to carry out the duties of section 17A.10 and for activities and duties required under chapter 31B.