I get that by selling $300 book bundles, he only needs to sell 1/15th of what he'd need to sell if the book were $20; and that of the people who would buy the $20 book, there are probably more than 6% of them who will buy the $300 book; but it's still pretty offputting.
I'm certainly glad that I didn't have to buy K&R's C book as a $200 package complete with "file templates" and an "audio book" and "an exclusive skype session with the authors who will give you personal feedback on your C program"!