A lot of 'discussion' here on the merits or otherwise of various sources for books. Here is a place I use fairly often:
AbeBooks Official Site - New & Secondhand Books, New & Used Textbooks, Rare & Out of Print Books
Whilst it may not be relevant to John Farley's new book, I don't doubt that some of you will find it useful for other rarer and unusual stuff.
It is a portal for all sorts of book suppliers and is often the only place I can find out-of-print or similar books. I guess it works in a similar way to the 'Available from these sellers' link when Amazon perhaps don't have the item you want. The great thing is it includes loads of small dealers, all over the world, and whilst the focus is probably on second-hand books there are many new ones as well. And the new ones have often disappeared from the larger retailers, so you have a chance to get a copy.
I used the site to track down a very good second-hand copy of an out-of-print book (that had only first been published in 2001!) in a bookshop in California! The crazy thing is that this hard-cover book, with P&P, came to half of what some UK dealers wanted for their copies of the second-hand soft-cover version! I also had another book shop in Washington offer to go through their several copies of a book I was after, and put together the best dust-cover with the best hard-cover book and send it to me at no extra charge. So, you can get some really personal service and help support these dealers.
If you are UK based, like me, you may wish to tick the " UK First" box in the search requester on this site - that will put available UK-based sales at the top of the search results. As I have indicated above though, sometimes the best deals are not necessarily the ones closest to home.