e-ink is hugely expensive. This saves them a ton of money. but don't turn it on negative contrast or you'll be replacing toner cartridges like mad.
Doofus. e-ink doesn't use toner, it uses ink. You don't put toner carts into your ink-jet printer, do you?
Turning on negative can cause the e-ink to leak out of the e-book and get all over your hands. Impossible to wash off. And don't get me started on the damage that running an e-ink device through the washing machine with a load of whites can cause.
E-ink is expensive because it is a dead-end technology. There are so many more uses for LCD displays that volume drives prices down. e-ink works for e-book readers, that's about all. You can read your e-books on a full-function tablet device, so why buy something locked to one vendor? (Yes, I know that e-ink is very good for reading things so e-book readers have a niche.)