This may be old news, but I found it interesting. I have a copy of the book "knowing bass". I read it cover to cover and found it very interesting. I was wanting to reread it, and cant find my copy. I decided to just by a new copy, until I searched for it. If you don't understand, do the search yourself. For reference, I think I paid between $10 and $20. At least KVD Winning strategies is still reasonable.

I had a quail book I was in go up in price like that. A second addition was published and the first addition came back down some, but books can get ridiculous. If you can find a half price book store that is still open you might be able to find one.

The book is out of print. The author worked for Berkley, he used proprietary information to write the book. The company got bought, and shortly after the book went out of print. I've reached out to Keith Jones multiple times to hear the full story, but never heard back from him. I can only assume the new owners were not okay with their IP being shared for the financial gain of one of their employees.

Anatomy of a Bass is a solid read also

I did a search and there just might be a copy on the web somewhere for virtual reading, though it is probably not copyright legal.