Why do economists and policymakers rely so heavily on willingness to pay (WTP) and willingness to accept (WTA) to measure value? Willingness to Pay explores the foundations, strengths, and limitations of these widely used tools in economic valuation. It examines how WTP can reflect individual well-being and autonomy, while also highlighting the distortions caused by lack of information, behavioral biases, or inequality. From pricing everyday goods to valuing the environment, child welfare, animal rights, and even the use of social media, this monograph reveals the complexities behind putting a price on what truly matters. When WTP falls short--due to poverty, inexperience, or systemic flaws--should we still trust it? And what happens when WTA far exceeds WTP? Through clear analysis and thought-provoking examples, this work challenges conventional economic metrics and offers a nuanced guide to understanding value, welfare, and justice in a market-driven world.