The spell books have not yet been released. The plan during the Kickstarter was to have them available at GenCon, but I don’t know if that will still be the case with the delay on the game.
Once the game is out they will be purchaseable from the cryptozoic store, again, unless plans have changed.
That’s my understanding, yeah. You could either get it via the Kickstarter without the box, or at GenCon. Either way we understood that GenCon people would be getting it first.