You can make smaller ones for much much less. I’ll post pics of mine a bit later but waveshare 7.5” display in a photo frame and almost any ESP32 dev board and you are set for less than $100 (along with suitable HomeAssistant and ESPhome infrastructure to support it). The original article is a very slick bit of work, so well done
The article also mentions using jailbroken kindles which I assume should be the cheapest way to get a decent sized epaper screen with builtin connectivity.
edit: https://github.com/sibbl/hass-lovelace-kindle-screensaver
Yep, it’s super cheap. I wrote about mine here:: https://franz.hamburg/writing/kindling-e-ink-dashboard.html
You can also buy some for less than $100.
I can vouch for the reTerminal: the build quality is excellent, and they come with a battery, sd card reader, and some sensors: https://www.seeedstudio.com/reTerminal-E1001-p-6534.html
Gonna piggyback here to second this and chime in to say I went with the BYOD screen linked within your link for $49 (SKU 104991005). It's definitely more barebones and probably not even as cost-effective if you're still planning on buying the "lifetime" TRMNL API access.
I don't have easy access to a 3d printer, so I just have mine sitting on an extra phone stand I had lying around that can be had for a few bucks from Amazon.
I couldn't be happier with it and am thoroughly enjoying my complacent, lazy solution :)