I'm not a kobo owner, but I've bought multiple hundreds of dollars of fully legal ebooks off Humble Bundle. Some of these collections are actually sourced through the Kobo ebook store for the backend delivery. Other collections are non-DRM epubs. I'm currently reading through the Martha Wells collection (Murderbot, Ile-Rien series). It was $18 for 14 of her novels/novellas. Prior to that was a collection of Hugh Howey (Dust, Sand) and Neil Stephenson (Seveneves) There's currently a Robert Silverberg collection of 32 books for $18 I'll probably pick up.