Kickstarter definitely would have been a better way to launch. Especially since the funding goal to get a book illustrated would be less than $2k on the conservative side. If I were doing it again I would probably use KickStarter.
Making the front page of HN was unexpected. I'll have to update the post once I see how much it improves sales.
Incidentally, this post may prove to be another great channel - imagine this wasn't a post-mortem, but a pre-Kickstarter update on the process & journey of working on the book...of course, making the HN front page these days requires quite a bit of luck.