Dollar General in the US based their entire business model on tricking people like this. They sell stuff at 75% the price of places like Wal-Mart, while hoping people won't notice that the item is half the size of the one at Wal-Mart so you end up actually paying 150% of what you would if you went somewhere else. They also run all the local stores out of business so that people don't have any other nearby choices. Very scummy business.