Being that the movie was released less than 40 years ago, and that the majority of actors were young and at the beginning of their film careers, there's a good chance of having them sign something for you if you can't find one you feel is authentic! I don't recall any of the main players passing, except for Lynnette Thigpen (the DJ) and Roger Hill (Cyrus). Many of the actors here are well known for readily signing for their fans.