For sales of timber which include a provision for purchaser credit for construction of permanent roads with an estimated cost in excess of $20,000, the Secretary of Agriculture shall promulgate regulations requiring that the notice of sale afford timber purchasers qualifying as “small business concerns” under the Small Business Act, as amended [
15 U.S.C. 631 et seq.], and the regulations issued thereunder, an estimate of the cost and the right, when submitting a bid, to elect that the Secretary build the proposed road.