I'm nearly done with revision 4 of this book. I will be posting the PDF and HTML version on this site, as usual. However, I am also going to publish it on Amazon in both dead tree and Kindle formats. If possible, I will make other ebook formats, but I'll see how that goes.
Pricing for the physical and Kindle versions hasn't been decided yet, but you'll probably be able to buy it just by saving your pocket change for a week or two.