The commission shall expend an amount at least equal to that raised by two mills of the assessment provided for in section 4.1-13-15 to contract for activities related to domestic wheat policy issues, wheat production, promotion, and sales. The contracts may be with no more than two trade associations that are incorporated in this state and which have as their primary purpose the representation of wheat producers. The contracts must require that any trade association receiving money under this section pay from that money all dues required as a condition of the trade association’s membership in any national trade association. The contracts must prohibit any trade association receiving money under this section from eliminating any dues required as a condition of membership in that trade association or from reducing such dues below the amount required for membership as of January 1, 2005.