I don't mind supporting the shop, and do it all the time, but doesn't mean I will pay $80 on a book (why create more waste? consume more? Plus PADI is the one making the big bucks), if I can buy used, or even get for free.
TDI offers the course on-line for about $120. I agree about 'owning' yet another paper book. Once you go over the basics, the refreshing your memory (if you're math challenged) of the details from free on-line sources is too easy