When it comes to open tech, I really think we need to change our way of thinking.
We have a habit or comparing the price of alternatives against the market leader (in this case Kindle) and assessing value on that basis, while at the same time forgetting that Amazon claws back a huge amount of profit after the point of sale on books - specifically because of their closed ecosystem. The monopoly allows them to subsidise the device.
If we are buying open devices which aren't locked down, the companies selling those devices have to actually make all their profit up-front on the device itself, and so it's naturally going to feel comparatively more expensive.
We have to remind ourselves, if we value freedom we need to be prepared to pay a premium for it.