(a) The purchaser shall make an initial payment in an amount set by the board’s rules for land sold under this chapter.
(b) The balance of the selling price shall be amortized over a period determined by the board not to exceed 40 years together with interest at a fixed, variable, floating, or other rate or rates determined by the board.

(c) The purchaser is entitled to pay any or all installments still remaining unpaid on any installment date.
(d) In an individual case, the board may postpone for good cause the payment of the whole or any part of an installment of the selling price or interest on the selling price on terms the board considers proper.