I asked them about this a few months ago. Here is what they told me.
<In regards to #3, I kept selling out of my pre-order quantites and
when I last tried to up my # through diamond, they were listed as being
sold out as well (their quantity gets turned into the publisher before
the book hits as well so he knows how many to print).
I believe #3 is going to be re-solicited so it's possible I'll have
it back up again next week - if you can, hold off for a week or so and
I'll try and get this squared away.>
That was from the co-owner of Graham Crackers. What does it mean? Keep checking. It will probably be available for pre-order again soon.
Hope this helps!