That's entirely dependant on the economy. If the average consumer is doing well then what you are saying does happen.

But if they are not doing well financially, like right now, then stores begin to compete more. I'm starting to see this locally myself in grocery prices. Some things are actually coming down slightly, at least for the moment. I expect with the increasing price of diesel prices will skyrocket again, but maybe we'll get lucky and companies will have to eat the cost this time. Everyone is so broke right now they may not be able to pass the cost on