I never thought about looking for books on eBay. But I do recommend spray adhesive as long as it's archival quality safe. The folks in the art store can usually confirm whether or not it is.

Izile, you might even try posting on freecycle in your area.
I say this because I actually give books away myself (in my area) from time to time. I am sure others do as well.

Hi there,
I use Golden's soft gel medium (matte) or fluid matte medium to glue my pages together, depending on the weight of the pages. When I make board books, the gel medium works the best. It's soft and creamy and very strong and it stays moist long enough for me to cover a larger area without drying before I'm ready to put the pages together.
I find the fluid matte medium is better for regular book pages. It has more of a consistency of white glue, but a little thinner. When I glue pages together, I put them between wax paper and then close the book and weight it down. This helps me to keep wrinkles to a minimum. But before you create any beautiful artwork, I would suggest gluing a couple of pages together in the back of the book and testing whatever adhesive you use to make sure it works with your book. You can find some more ideas on my web site at karenswhimsy.com/altered-books/ .