Suppose a retail chain, e.g. Walmart, had a customer loyalty card with a small display and a near-field sensor or small camera.<p>Suppose that as a product ages on the shelf the price was reduced on a daily or hourly basis.<p>Suppose the price change could be detected and displayed by the loyalty card.<p>Now a shopper could "scan" a product and choose the particular can/bottle/box that had the best price at any given time.<p>This is just the "best by date" taken to a new electronic extreme.<p>The card could also be "loaded" at the store entrance showing "the best deals" currently available right now.<p>Bonus discounts could be added at checkout based on the number of "best deals" chosen.<p>This would benefit retailers as it would move older product before it expires. It would also benefit retailers if they had a better age/price policy than another store.<p>Such a device would be easy to make using an e-display, a micro camera or near-field sensor, in a form factor about the size of a credit card. Indeed, it could be a Walmart-branded Visa credit card. The current credit cards already carry a processor capable of handling this.<p>I'm pretty sure eInk can be configured into a credit card format, using minimal, externally supplied rechargeable power.<p>Surely someone can make this happen.