Quick, right this second there are FIVE copies of Mark Hiner's Up Pops available between $14 and $25. Snap 'em up!
Tarquin Books has reprinted Mark Hiner's Paper Engineering. Good for U.K. customers, not so good for U.S.A. customers. Possibly it will be available at Book Depository, although it's not yet up on their site.
But that's okay, there are lots of used copies under $25 right now on Amazon.
Obviously, this information is time sensitive. Books may be sold by the time you are reading this post!
Extreme Cards and Papercrafting: pop up cards, movable and mechanical cards, digital crafts and unusual papercrafts.