I'm sure that the printing of the book cost a bit as well. From the picture and description it seems to be and actual hardback book that the DVD is contained in. I imagine the printing costs aren't all that cheap, I assume they printed enough that they are still making a decent profit but I'm sure it's not as much as alot of us would believe.

...but I didn't order it, my housemate did. I'll just watch his copy.