What you're trying to accomplish would require modification of the database they're using for inventory and pricing information. As you might imagine, large retailers such as the ones you've mentioned go to great lengths to protect the integrity of this information.
Barcodes are encoded numbers that are scanned and then used to perform a database query that asks "what item is this and how much does it cost?" They don't contain any information other than the item number since they're static and prices are dynamic. A database query is a necessary step in the process and is what you'd have to compromise to accomplish your goal.