I guess this depends a lot on country and culture. In Spain, in the supermarkets I usually go to, price tags are standard, black-and-white and uniform, just telling you the price and other standardized information (like price per kg). To grab your eye towards certain products, supermarkets add additional signs near the price tags (but not instead of them).

This is a typical example: https://cflvdg.avoz.es/sc/X71nZnU3spbY_97PpRRHtVnNB20=/x/201... - the price tags are standard, but the yellow sign with the eye ("you have a keen eye!") draws your attention to a particular tag. If they want to draw your attention even more they will use a larger sign, no problem.

By the way, eInk price tags in supermarkets here are common. Far from ubiquitous, but common.