Maria purchases a premium brand coffee at the grocery store for 8$. which would be considered a substitute good

A substitute good for a premium brand coffee would be a regular coffee or even other beverages such as tea.

Explanation:

In economics, a substitute good is that substitute for another, while one of them may be consumed or used in place of the other in some of its possible uses. Classic examples of substitute goods are margarine and butter, or oil and natural gas. The fact that one product is a substitute good for others has immediate economic consequences. One good can be replaced by another, the demand for the two classes of goods will be considered together because consumers can exchange one good for the other if it becomes advantageous to do so. Thus, an increase in the price of one of the goods will cause an increase in demand for its substitute goods and a decrease in the price will cause a decrease in the demand for its substitutes. Thus it can be predicted that a rise in the price of cars will increase the business of the public transport service or that the fall in prices of mobile phones will mean a drop in demand for public phones.