$20 on a book with advice that you never put to use is as good as burning the pages.
$200 on a course that changes your life by guiding you to action and discovering the benefit is 100 times more valuable if the course changes you. If it doesn't return it for a refun. The price of shipping still greater reward than the book on a shelf.
With the book on the self you always have a touch of guilt that maybe, if only you tried it, it can make a huge difference in your life. Once you've done the course you know one way or the other.
Yes spending money on a course is a risk and a potential reward for yourself.
Every course you have mentioned has a money back guarantee. Usually all you pay is the postage, which is more or less the same as the price book.
Alex