We've had digitized (eInk, LCD) price tags for well over a decade now. They just haven't seemed to take off anywhere except for Kohls (at least in my area).
I noted in an earlier comment that I recently saw virtually complete usage of e-ink price tags at Best Buy (some fairly large - like tablet display size). But Kohls is where I first encountered them in the wild - they seem to be one of the earlier adopters.