I would have felt better about Ebook pricing if you included the kindle version. I keep my reference books on a kindle with a 2 month battery. My tablets are always out of power when I need them.
I'm limited to reading this on my laptop and my phone now. It looks like good content. shame about the format.
That, and the difficulty (for me, at least) to get a decent book filled with screenshots and examples in epub / mobi, is the main reason why a chose to not produce Kindle-ready formats.