I just found out that Humble Bundle has a book bundle for Terry Pratchett’s Discworld. A 39 book bundle that is redeemed through Kobo.com.
Edit: Only available in the US.
https://www.humblebundle.com/books/terry-pratchetts-discworld-harpercollins-books
I’ve been able to strip the Kobo DRM out of a couple of book bundles using Calibre. Haven’t bought this one yet, but I’d assume there wouldn’t be a problem.