Did you read the OP's second sentence? The PapiRus displays are in general quite compelling (I've been tempted), but the OP already dismissed them as too small. I did, but he dismissed as too expensive. It didn't seem that far out of range... but you're right, my head focused on power not size. I a...

There was a product released a bit ago... PapiRus http://www.pi-supply.com/product/papirus-epaper-eink-screen-hat-for-raspberry-pi/ It's $41.66 – $81.01 up to 2.7" if you don't need larger. There was also PapiRus with Zero /http://raspi.tv/2016/playing-with-papirus-zero. I was considering these, but...