You can purchase the ebook from your favorite retailer via this link:
At the time this blog post went live, some of the retailers aren’t showing it on their electronic shelves yet. Just check back a little later. It will eventually appear. The paperback version is already available on Amazon, and will be available from other bookstores in a few days, as will the hardcover version.
UPDATE: As of 16:20EST on 12 June 2019, it is finally LIVE on KOBO!