Scarcity can be hard to judge. For instance white gold is worth more right now than yellow gold because it is in style. when I wear gold I only wear yellow gold because everyone my age only wears white gold. so within scarcity there are principles of popularity and principles of equivalent products targeted to certain users at close but not equal price sets. Think mcrib vrs the six dollar burger from Carl jrs. Or happy meal Thursday vs kids eat free on tuesdays at IHOP. Marketing similar equal products but to different users based on popular trends among different social classes. Location has a lot to do with how marketing takes place in different regions.