At all points of the modern marketing system people have formed associations and eliminated various middlemen in order to achieve more efficient marketing. Manufacturers often maintain their own wholesale departments and deal directly with retailers. Independent stores may operate their own wholesale agencies to supply them with goods. Wholesale houses operate outlets for their wares, and farmers sell their products through their own wholesale cooperatives. Recent years have seen the development of wholesale clubs, which sell retail items to consumers who purchase memberships that give them the privilege of shopping at wholesale prices. Commodity exchanges, such as those of grain and cotton, enable businesses to buy and sell commodities for both immediate and future delivery. Methods of merchandising have also been changed to attract customers. The one-price system, probably introduced (1841) by A. T. Stewart in New York, saves sales clerks from haggling and promotes faith in the i