My coworkers and I were talking about the concept of voluntarily paying more than you need to for something. As an example, I can buy a locally grown organic apple from the farmers market for \$3 or a conventional one from the grocery store for \$0.50. We can say that the \$0.50 apple is a basic level of consumption- society agrees that I deserve that apple as a human right (or, we can expand the argument to a basic level of consumption including shelter, food, etc). Since I paid \$3 instead of \$0.50, I paid an extra $2.50 for the luxury if it being a special kind of apple I prefer.
We called this amount "marginal luxury". Does economics have a proper name for it? Is there a reliable source of how much of an economy, say the US, is marginal luxury?