Very few customers are buying electrophoretic displays because of their many limitations. That's the real reason why prices are so high.

In 2006, a 6" display would have cost maybe 10 grand, maybe even more. Today it is in the order of $25 in volume and that's purely because of the volume behind it. Step off the volume path and into hand kerfed like the 42" you mentioned and suddenly it'll be $2000. It is all about volume.

If you want it cheaper, put an order in for a million displays and that'll justify someone's effort to build an actual automated production line for it and it will drop the price by an order of magnitude.