You can pre-order ebook, audio, trade paperback and hardback of Operation: Endgame.
They are add-ons, since they will not be delivered until May 2017, and physical books will require postage. However, both trade and hardback come with the ebook included.
Scroll down to the point where it says 'Unlocked $15,000' and you should find the pricing for all the options. Then simply follow these instructions.
Click the “manage your pledge” button on the campaign's page. Then increase your pledge by the amount needed to claim the add-on(s) you want. It is not necessary to change you tier. Once the campaign is over, we'll send out surveys where you let us know what you ordered.