Actually, as a customer, I can confirm that all the Whole Foods Markets I’ve seen do have digital pricing displays for most things - they are based on e-paper technology.

But you don’t want prices changing between the time a customer has picked up a product and the time they get to the checkout. And then there’s the whole problem of the in-store prices not matching the published circular prices.

So, lots of issues to work out there before dynamic pricing can work well in a physical store.

If the price drops between picking up an item and paying for it, I don't think anyone would complain.

And you can handle the other direction with a lag. Charge the old lower price for 30 minutes.