I know these kind of strategies (get early engagement / validation) are promoted in this lean startup era but it leaves me a bit disappointed (and I think the more people use this strategy, the less accepted/effective it will become). But that is me and if it works for you and enough others, the democratic process of HN should prevail :)

I do like the idea, also because you plan to explore (in a fashion that does not require full serial 'consumption' of the book) various JavaScript toolboxes and libraries and even server-side stuff. I can't put any sensible price tag on it though.

Side note: in a 80/20 world, 10% finished would mean that roughly half of the draft is written ;)