Many/most of the sales are not at a significantly lower cost than most of the time. Prices go up for a month or two before Christmas. For the sales, you might get a good discount on a single item in a store, which is when they expect you to buy other things too to make up for the single sale. Other times many things will be at slight discount, but they might at operating cost or much lower profit margin. You are expected to buy things which are not on sale when the sale is real, otherwise the price was raised for a while and only lowered for the sale. I have also heard that some things are made with lower quality for sales, so you may not be getting the normal quality.