I scoured the wave share site for all the other e-ink screens and there're many cheaper ones.
You can get small e-ink screens (without a HAT, requires adapter ~10$ and dev board which is necessary anyway) for much cheaper.
5.8 inch is 40$
800×480, 7.5inch 50$
400x300, 4.2inch E-Ink raw display, three-color 26$
The cheaper ones are cheap because:
1) Each size comes in a low res and a high res variant, the low res ones are a lot cheaper
2) No HAT, so no built-in dev board for the PI. You do need to somehow connect it to your dev board. An adapter with SPI costs 10$, a dev board with esp8266 that has built-in adapter costs ~18$. Both are officially from wave share available on their site as well
3) All boards below 7 inch are relatively affordable. After that the price increases are huge
4) Not sure why, but price difference between black/white and 3-color is negligible. So feel free to pick a 5 inch tricolor screen for like 40$!
1. Refreshes are much slower on 3-color eInk panels than on monochrome ones (eg: 20 sec vs 2)
2. Partial refresh on 3-color panels is rare and quickly gets messy around the edges. Partial refresh on monochrome panels is a relatively simple thing to do.
3. Greyscale on a 3-color eInk screen is VERY VERY VERY hard! Officially it is not supported at all. By any 3-color panel. I made it work [1] but even then, it is very very slow (bordering on a full minute per refresh).
4. Stock waveforms are rarely good. And almost no vendor will give you proper temp-compensated partial update waveforms. Developing your own waveforms for monochrome panels is easy and simple (~day). Developing your own waveforms for 3-color panels is a lot of work (~weeks + more weeks once you need to support more than just "21-25 celsius")
You can get small e-ink screens (without a HAT, requires adapter ~10$ and dev board which is necessary anyway) for much cheaper.
5.8 inch is 40$
800×480, 7.5inch 50$
400x300, 4.2inch E-Ink raw display, three-color 26$
The cheaper ones are cheap because:
1) Each size comes in a low res and a high res variant, the low res ones are a lot cheaper
2) No HAT, so no built-in dev board for the PI. You do need to somehow connect it to your dev board. An adapter with SPI costs 10$, a dev board with esp8266 that has built-in adapter costs ~18$. Both are officially from wave share available on their site as well
3) All boards below 7 inch are relatively affordable. After that the price increases are huge
4) Not sure why, but price difference between black/white and 3-color is negligible. So feel free to pick a 5 inch tricolor screen for like 40$!