In canon, I believe, the Book of Nod that was published by White Wolf IRL back in the 90's mirrored the publishing of it in-game as well, after it was stolen from Beckett(I think, but maybe it was Aristotle. If it was Beckett, that guy should really stop writing things down)

Sort of wink-wink, the Masquerade was broken, so you have the real thing in your hands sort of thing.

So, I'd say that as of that printing, the Book is now commonly available to those looking to get their hands on a copy.