Perhaps it is because I work in a business school, but the soft drink vending machine near my office is helping teach us all the economic theory of supply and demand.

You see, it features two buttons, both of which dispense an identical 20oz. plastic bottle of Diet Pepsi. However, the first button dispenses the Pepsi for 1.10, while the second costs an additional .15 for a total of 1.25.

So, early in the week, while supply is high in the newly stocked machine, we can drink Pepsi for 1.10. But as demand increases throughout the week and supply decreases, the price jumps to 1.25.
In reality, it’s probably just a mislabeled button that used to be Snapple or something, but still, I’d like to think they planned it.