The contract may provide that the association may sell or resell the fishery products delivered by its members, with or without taking title thereto; and pay over to its members the resale price, after deducting all necessary selling, overhead, and other costs and expenses, including interest on preferred stock, not exceeding eight percent per annum, and reserves for retiring the stock, if any; and other proper reserves; and interest not exceeding eight percent per annum upon common stock.