Who needs an Amazon Kindle when you can build one yourself? The Waveshare e-paper HAT comes in numerous display sizes ranging from 1.54-inches to 9.7-inches. The HAT communicates with a Raspberry Pi via SPI, UART or USB depending on the model and comes in a choice of two, three or four supported colours. The Waveshare e-paper HAT costs between US$15.99 and US$169.99 and ships worldwide.
https://www.notebookcheck.net/Turn-your-Raspberry-Pi-into-an-e-reader-with-the-Waveshare-e-paper-HAT-an-expansion-board-that-starts-at-US-15-99.421477.0.html