In Australia, I was able to get a copy of said book, in a JB HIFI store in South Australia. It was on a clearance table for $20 Aust. I snatched it up.
The guys that spent over 40,000 hours of playing and testing to come up with the book deserve a huge 👍 as information from there was very helpful.
However nothing beats the experience and help from these guys on these forums, as you can ask a direct question and some-one would be nice enough to answer it for you, or point out a thread its been asked in before.
Good Luck finding a copy, being the game is 'OLD' in comparisson to what stores would be keeping now. (and yes I do know you can still by GT4 new however the book would be a lot harder to find).