[Quoth]

We've (Ireland) had them in Aldi, Lidl, and Musgrave owned stores (Centra, Supervalue, Superquinn for quite a while. They update them from a handheld terminal. There is a rechargeable battery so maybe the terminal inductively charges them. Obviously they only need power when being updated.

Here the paper tag, or any price on the product has to be charged, if the checkout price it higher.

It's not very speedy but faster than fiddling with paper. Also they can scan the barcode on the product at the tag location to get the settings for the tag – I've watched the process.

The larger panels are quite grey compared to small tags. The white + black + one colour (options other than red) panels are somewhere on the Eink Corp site. Resolution doesn't seem great, but appearance is better than a 1981 Epson dotmatrix printer.