https://www.youtube.com/watch?v=MsbiO8EAsGw
Eink could have changed the world, yet the only eink display I and many people have it our kindle.
They were the first to build the technology to bring refresh times for writing near the 50ms mark, and hold the patent about it (AFAIK they license this patent to other builders who use Canvas).
[1] https://support.remarkable.com/hc/en-us/articles/36000264751...
Economy of scale makes weird pricing happen.
Right now on digikey you can buy a "SWI25-12-E-P5" 25 watt PSU for $11.95, or a "KTPS12-12010WA-VI-P1" 12 watt PSU for $12.21. Both are wall mount class 2 supplies, level 2 efficiency standards, even the same connector. The cheaper one has a longer cord, LOL, as yet another weird example of economies of scale.
If your application requires 10 watts, a 25 watt supply will quite happily provide 10 watts and run extremely cool for a long time compared to a 12 watt supply being asked to provide 10 watts.
I will admit that one mfgr chased safety approvals for euro countries and the other chased safety approvals for USA/Asian countries, but for hobbyist one off purposes, something that passes TUV/CE is approximately as good as something that passed UL, and if you want to sell commercially in the US its usually a paperwork transaction to cross approve something. A bigger problem is X% where X is pretty large, of chinese mgfr equipment has fake safety marks. So for hobbyist purposes you're far safer using a genuine TUV approved supply in the US than graymarket gear with a fake UL mark. So there are minor differences. It would be non-trivial to design something that could pass TUV but fail UL, although someone out there has probably succeeded in the past.
The real world market is not magically 100% efficient, so you can absolutely pay 26 cents more for a supply with a shorter cable and lower power output.
Unfortunately vendors are somehow constitutionally incapable of providing useful technical information for eInk displays. It's so frustrating that there's a huge graphic extolling it's FPGA based refresh technology but actual technical information is almost completely absent. Why can't I just get a datasheet?
I'll summarize here so other people don't have to grep through this mess.
There are 3 modes, GC16, A2 and A2+, no technical information is provided but there are some tiny (simulated?) screenshots. It appears that mode A2, the "high refresh rate" one is purely black and white with no gray.