You can now find the box set through both comic shops and major book retailers.
As of this writing, there appears to be a few copies left on Amazon, and none on B&N. I would recommend checking with your local comic shop to see if they can order it.
Thank you to everyone who pre-ordered, ordered a box from me directly, or is planning to buy the set! It’s been a real joy designing this box and releasing it into the world. I hope it looks lovely on your shelf.