Economic Definition of tie-in sale. Defined.
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Term tie-in sale Definition: A type of sale in which consumers can buy one good only if they purchase another good as well. For example, if your grocery store sells you a bag of tea with the condition that you buy a pound of sugar, that would be a tie-in sale. Because they allow a monopoly to increase its profit over what it could make by selling the two goods separately at constant prices, tie-in sales can be used to price discriminate. However, it is important to realize that there are other reasons for tie-in sales other than price discrimination, such as to increase efficiency. For example, when we buy a car, it comes as a package of several goods (tires, engine, etc), which would be very difficult (and inefficient) for consumers to assemble if they were bought separately.