If you are bidding commercial and industrial work an $80 dollar tool is pretty much a nothing burger. Have you seen how much is the cost of a new Greenlee 881 EMT bender?
The DEWALT Electrical Estimating Professional Reference Second Edition is a practical guide for electricians to successfully estimate and bid jobs anywhere. Based on real-life experience from the angle of a professional electrical estimator, this detailed book covers every step of the process...
I think it depends on where you're at as an estimator and what you're looking to learn. What is your goal or what do you want to learn from any books? I agree that regardless of where you are the $80 will be well spent on the book.
I don't have any specific book recommendations for commercial estimating. I primarily learned from a friend, and although I initially started with a few books like RSMeans' Electrical Estimation Methods I found that it didn't offer much new information compared to their cost book notes and references. In my opinion, it was a waste of time and money. The fundamentals of estimation are not overly complicated and don't necessarily require a lengthy 300-page book. I'm not suggesting that references aren't necessary to get started, but it seems like some books are simply inflated in size to justify their price. Certainly, this may not be true for all those estimation books. I think the most important requirement is field experience. If you have also someone who can help you, that would be ideal.