Those who can afford it but choose not to buy it. Individual demand: the relationship between the price of a good and he quantity demanded by one person. Market demand: the relationship between the pice of a good and the quantity demanded by all buyers. Consumer surplus: when people buy something for less than it is worth the value (or marginal benefit) of a good minus the price paid for it, summed over the quantity bought. Marginal cost: minimum price that produces must receive to induce them to offer one more unit of a good or service for sale: minimum supply price determines supply supply curve is a marginal cost curve. Individual supply: the relationship between the price of a good and the quantity supplied by one producer. Mario is willing to produce the 50th pizza for , his marginal cost of that pizza that pizza.