Final answer:
An economist would refer to the situation where a shopper gets a good deal on a product as consumer surplus, which represents the extra value gained from purchasing at a lower price. This concept is important in economic theory and can be influenced by seller offers such as money-back guarantees.
Step-by-step explanation:
When a shopper gets a good deal on a product, an economist might describe this as consumer surplus, which occurs when consumers are able to purchase a product for less than the maximum price they are willing to pay. The concept of consumer surplus is central to economic theory, as it reflects the value that consumers gain from making purchases at a lower price point. Additionally, when a seller provides offers like a money-back guarantee, it tends to boost consumer confidence and can lead to an increase in sales by reducing the perceived risk associated with purchasing a product, especially in the case of online or mail-order sales.