You would pay $40 for a T-shirt if it were some sort of collector’s item you could resell. You would pay $100 for running shoes because that’s less than $15000 for knee surgery, and you like having comfy feet. You would pay $150–300 for an ounce of weed because you know what weed is like, and you like it, and the price is driven up by legal issues. But what justification can you come up with for spending $200 on what is essentially a productivity tool, if it won’t necessarily make you more productive?
But book stores, unlike the company that produces mocl, won't give my money back if I find that the book didn't help me within the first 30 days.
So in this case, it's even a relatively safe gamble (assuming of course, that the company does in fact, honor the 30-day money-back thing).