I bought physical copies of several of them (the “FreeBSD Mastery: Jails” book, “FreeBSD Mastery: Specialty Filesystems”, “FreeBSD Mastery: ZFS” and “FreeBSD Mastery: Advanced ZFS”) on FreeBSD Mall.
I finished reading the “FreeBSD Mastery: Jails” book, and am currently reading the “FreeBSD Mastery: Specialty Filesystems” book.
I also recently bought the Total Mastery eBook bundle of his from his Tilted Windmill website. It includes eBook versions of the above books that I already have in physical copies, along with a bunch of other eBooks.
In the future I might buy physical copies of more of his books. There is something special about physical books that makes them far more comfortable to read for me than to read eBooks even though I have a eBook reader with eInk. The ability to flip through a physical book, and to feel the physical dimensions of the book adds something for me that eBook readers cannot.
I also want to investigate whether it is possible to donate books to some libraries. I think as a community we could buy IT books that we particularly like, and donate them to libraries, to make them available to more people. It would be especially nice to help books about FreeBSD and OpenBSD reach more people.