I don't usually suggest ideas that involve tearing up books but in this case, it seems the cheaper the book, the better the look. Try a bargain bin somewhere or local charity shop for a trashy novel with an interesting cover.
Also, it seems to be easily transferable to other paper media like magazines or prints so it doesn't have to be books, that's if you feel the way I do about ripping them up.
Trashy Novel Wallets
Jump on over to ReFabulous for a complete tutorial and list of supplies needed.