I like to be able to price shop, but I do want to support the authors. So I use Kobo & Kindle, then buy it wherever it's cheapest usually.

Then I use epubor ultimate to convert to epub and read it on my generic e-ink reader. Some folks object to the licensing or whatever with epubor (unattributed GPL?) but it works, it's easy, and when Amazon tightens up the DRM they always find a way around it eventually.