Thanks everyone. The book is to be 1/4 the size of a standard 8.5x11 sheet of paper. So a total of 8 impressions on each piece of paper. It will have about 175-200 pages. Since the content will be constantly changing, and batches will be small, I don't think using a commercial printer makes the most sense.
I'll take a look at jpdfTweak and iTextSharp. I found a pretty good interim solution. The Mac program "Preview" offers a "Copies Per Page" option on the print dialog. If I set this to "4" and check "Two-Sided" I can print four books at once. It would be nice to be able to make them one at a time, but this is okay for now.
