Timber belonging to the state of Idaho may be sold at public auction by the state board of land commissioners, at their option, as follows: ten percent (10%) of the estimated value of the timber, after deducting the development credits attendant to the sale of the timber, shall be presented as a bid deposit, in a form acceptable to the state, on the day of sale. Ten percent (10%) of the purchase price of the timber, after deducting the development credits attendant to the sale of the timber, shall be due and payable within ten (10) days of the date of sale. This sum shall be retained by the director of the department of lands as a cash reserve for the duration of the sale or the director may, at his discretion, apply all or a portion of the sum as final payment or payments for forest products removed or to satisfy other contractual obligations. The balance of such purchase price shall be paid at such time as the timber is scaled and billed with interest computed from the date of sale to the date of billing at the rate per annum set by the state board of land commissioners. Lump sum sales may be sold for cash at the time of sale or upon such terms and conditions as the state board of land commissioners may prescribe.