Yeah, I'm discovering that now, lol. My "research" consisted entirely of searching for "ruby" and going through the first few pages. They were nearly entirely Kindle versions of established print books. Turns out.. Amazon prefers to feature books that actually sell ;-)

I've since discovered some cheap indie Kindle programming books and even a whole range of cheap O'Reilly "What is *?" books. So it seems there's a market but IMHO not a very mature one, so I look forward to giving it a go. Thanks for the support!