_The Function of a Special Class of Marginal Purchasers of Each Article._--In like manner there is a class of "marginal purchasers" of the article B, or the persons who pay for it so much that they get no net benefit or consumers' surplus from the purchase. If they did not buy this article, they could get something else that would do them as much good for the same outlay. It costs, let us say, only ten dollars in the making, and enough of these articles are made and offered for sale at that price to supply all customers who are attracted by the offer. The men who would pay more for it do not count. Each of the other articles in the bundle, when it is offered separately and at the cost price which competition establishes, represents a final utility to some one class of purchasers. Competition has made the whole supply so large that, in order to dispose of it, venders must attract the particular class who will take it at the ten-dollar rate. This class is in the strategic position of market-price makers for this one thing. They are the last class to whom the producers can afford to cater. If each of the five articles in the bundle costs the makers ten dollars, and if so many of each are made that they just supply the needs of the classes that will buy them at ten dollars apiece, the price of all five, when sold separately, will be fifty dollars. Most of the purchasers of each article would give more than ten for it if they had to, but some would not do so, and the producers cater to the needs of these marginal persons.