In terms of their hardware cost and software development/wireless network, it's much more than just Superstore. Superstore is indeed huge but it's just one part of a much larger gargantuan grocery conglomerate, Loblaws.

https://en.wikipedia.org/wiki/Loblaws

they operate with other brand names for non-superstore-sized regular grocery stores, and the T&T markets which are their own market niche: https://en.wikipedia.org/wiki/T_%26_T_Supermarket

From observing the behavior of my local superstore it also appears they're using the eink price tags on shelf in conjunction with some sort of software for planning shelf space and inventory, so it has some value to them other than just the manual labor to change paper price tags.