ECO204: Principles of Microeconomics Analyze how the law of demand applies to a recent purchase that you made. Describe how the product has changed in price and explain whether the price change is due to supply or demand. Did the change in price affect your decision to purchase the item? Class: ECO204: Principles of Microeconomics Required Material: Amacher, R., & Pate, J. (2013). Microeconomics principles and policies. San Diego, CA: Bridgepoint Education, Inc. This text is a ConstellationÂ™ course digital materials (CDM) title.