I bought an ODROID-Go Ultra a few months ago for about $70. This can emulate the NES, SNES, Genesis, Game Boy, and oodles of other consoles, and can play what are arguably some of the best games ever made. The Playdate is three times that price, and while I'm sure that some of the games are fun, I would have a hard time believing that any of them are beating Donkey Kong Country or Phantasy Star IV.
It might be an apples and oranges comparison, but in my mind they still occupy a similar niche.
I do think it's beyond "impulse buy" for sure, though.
Even better, the creator supports educators super cheap
https://www.lexaloffle.com/pico-8.php?page=schools
Yea, it's not custom hardware, but you can share your creations with everyone since it runs on Web, Mac, Windows, Linux, Android, iOS and there are lots of cheaper devices that will run it if you want a handheld.
https://www.lexaloffle.com/picotron.php
With no technical upper limit on file size (as well as being able to export for other OSes) you could, in theory, publish a full game from this.
I bought mine pre release so it was like $50 cheaper even with the cover I think, but I would still pay the increased price for it. I thought it would collect dust, but it really is a great way to pass the time on the train. It scratches the original Gameboy itch for me without the needless stares from actually carrying a Gameboy.
I just wish they would release the docking station for it. I charge it next to my bed, so it could serve two purposes.