Whenever you go to the store, explain that you have to pay, with money, for the items you are buying. That way, your child won’t think it’s all for the taking. And resist buying things for your child on an impulse. Seeing you do this will make him think it’s to be expected.
Rather than forbidding your child to touch breakable items, let him hold them—for a prenegotiated length of time. “Yes—you can hold the ceramic duck, but you need to put it back after we’re done paying.” This will prevent him from seeing such items as forbidden fruit.
When in a store with your child, keep him in the cart as much as you can—that way, you can more easily control his impulses. As you shop, allow him to hold the items you’re going to buy; don’t let him run around pulling things randomly off the shelves. These items will seem essential to your child.