TRMNL's site seems to think there is not a cost-savings to build-your-own. They don't appear to include the licensing cost though. From their site:

> Making your own TRMNL from scratch is not an economically rational decision, but rather a labor of love. Our own team learned this the hard fun way while building v1 over 7 months, from Dec 2023 to July 2024.

> Here's what you can expect to spend per component:

> • Battery, $5 (unnecessary if you prefer plugged in)

> • EPD screen, $65 (see the Waveshare 7.5" on Amazon)

> • Microcontroller, $3-50 (depends if you build/solder yourself or leverage a PCB prototyper)

> • Enclosure/case, $3-20 (design + 3D print yourself or use a print farm)

Yeah, my BOM was $20 for the driver and $50 for the screen, plus $50 for the TRMNL license. About the same as the TRMNL I bought, in the end, though as you say the license is a big part of it.

My worry is about my lifetime license eventually turning into a subscription requirement.