I never know exactly when my books go into paperback form. I have to search the net the same as you. I usually order them at Amazon. (No I don't get freebees) I may be able to get them from the publisher if I want like a case of them.
I searched Amazon today and found they only offer my books from a third party. Odd. I ended up buying a bunch from Barnes and Noble. I think I now have them all but the bunny series. That will be in the next purchase.