Actually, you really don't understand. No business establishment ever wants to have an empty shelf or a "sold out" sign. It makes both practical and theoretical sense to raise prices to keep stock. Practically, a business wants to find EQUILIBRIUM between price and supply. If selling them at $300 causes you to be sold out for a month, selling them at $900 causes you to still have excess inventory when you get more supply, then you would want to sell at $600 to allow your stock to last as long as it takes to get new inventory. A retail establishment is going to price stock to match demand