I buy ebooks from Kobo, Kindle, small presses like Obverse, etc, and do most of my reading on my Kobo, though I have Kobo and Kindle apps on tablets. I rarely buy self-pubbed ebooks like the one the OP's talking about unless I already know about the author(s). Just because someone can get an ebook on Amazon, it doesn't mean they're actually capable of writing a book worth reading.