Realistically you’re not paying for the hardware when you buy the driver board, but rather the software baked into those boards.
The waveforms, and the algorithms that create waveforms, used to drive eInk displays at reasonable speeds and produce high quality images are highly proprietary and very difficult to develop. In theory it’s easy to make an eInk display an image, but doing that in a reasonable period of time, when transitioning from potentially any starting state, and handling the crosstalk between pixels, makes creating good images on an eInk display pretty hard to get right.
The waveforms, and the algorithms that create waveforms, used to drive eInk displays at reasonable speeds and produce high quality images are highly proprietary and very difficult to develop. In theory it’s easy to make an eInk display an image, but doing that in a reasonable period of time, when transitioning from potentially any starting state, and handling the crosstalk between pixels, makes creating good images on an eInk display pretty hard to get right.