That's the e-ink monopoly for you. Though you could probably use a slightly smaller b&w eink display with a second hand raspberry 4 to shave a lot from that number.

To be fair even if they could build a 10x larger e-ink panel factory it’s uncertain if they could shave costs by more than maybe 40% to 50% per panel.

And it’s very questionable whether there is genuinely 10x more latent annual demand for e-ink panels at that still not cheap price point.

If you have a Kobo (~ US$ 120 or even less used) you can run this using Cobalt https://github.com/BandarLabs/Cobalt/tree/beta/apps/birds

It seems like Kobo eReaders don't come with a mic.

You could probably use an ESP32-S3-PhotoPainter (which comes with a mic) to do this for even cheaper: https://www.waveshare.com/esp32-s3-photopainter.htm

Yes absolutely, the current Kobo one uses the Mac's mic. I work near a window on my Mac so this is handy without any hardware setup.