Nowhere, that I know of. Occasionally you see it on half.com or from third-party sellers; sometimes, for over $200. (Of which I get nothing, of course).
This comes up particularly now because Penny Arcade linked to the book today. But I probably get a couple of inquiries a week about it (thanks for your interest, Karl, Brady, John…).
The good news is that I hope to have news on its renewed availability in the next few weeks.
