As of summer 2015, the hardback edition is no longer available. Liturgical development is an iterative process; I would rather release the machzor as a digital file or a paperback book than as a hardcover book. Apologies to anyone who wanted a hardcover edition!
A few people have asked, so I also want to add -- there are also other Jewish Renewal machzorim which are fantastic. I'm particularly fond of the New Kehilla Machzor edited by Rabbi David Shneyer and Machzor Kol Koreh edited by Rabbi Daniel Siegel. (You can see an excerpt from Kol Koreh in this post from Reb Daniel: Malchuyot, Zichronot, and Shofarot.)
Days of Awe was designed with the needs of my own community in mind, and I'm thrilled that it's being used in a few other communities this year as well -- but if you are interested in Jewish Renewal prayerbooks or in machzorim in general, I commend to you both New Kehilla and Machzor Kol Koreh. With machzorim, as with everything else, there's no single way to "do Renewal."