I'll always support efforts at making education more accessible, but 90$ is pretty cheap for a textbook of this size. And it's a hardcover! And it's available

I'll always support efforts at making education more accessible, but 90$ is pretty cheap for a textbook of this size. And it's a hardcover! And it's available to read for free online, in its entirety, on the author's website. It's hard to beat this proposition.