As long as there's a tag on the shelf, I don't see why every item needs marked. I know there are still states with that antiquated law, but bar codes kind of did away with that need.
How many times do we go to a store knowing exactly what we need and how many times do we go in thinking, "there are several ways I can do what I need to do, let me find the cheapest?" If I have to take a salesman (or catalog) around the store with me, I'm outta there.
My smart-phone has revolutionized my shopping experience. I just scan the barcode and it googles the product to show me all the prices on the internet and other local stores.