In establishing the cost of cigarettes to the stamper, retailer or wholesaler, the invoice cost of such cigarettes purchased at a forced bankrupt or closeout sale or other sale outside of the ordinary channels of trade may not be used as a basis for justifying a price lower than one based upon the replacement cost of the cigarettes to the stamper, retailer or wholesaler within thirty days prior to the date of sale in the quantity last purchased through the ordinary channels of trade.