A City Guide To Pingnan for spillovers: when the costs or benefits associated with providing a good fall on individuals (or society) not directly involved in producing or consuming the good. substitute goods: goods related in consumption such that the two goods are alternatives to one another (e.g., tea and coffee). The demands for these goods are negatively related, which implies that increased demand for one good corresponds with decreased demand for that good’s substitutes. sunk costs: non-recoverable fixed costs, typically paid in advance of the decision to produce a certain level of output. supply curve: a graphical relationship between the price of a good and the quantity of the good suppliers are willing to provide at that price. A City Guide To Pingnan 2016.