The iTunes Music Store offers downloads of the Batman Detective Comics #27 Digital Comic Book for Mac or iOS for free. (Barnes & Noble, Google Play, and Comixology also offer digital editions for the same price.) That's the lowest price we could find and a great way to see the original appearance of Batman, which happened 75 years ago. It includes Batman's origin story from Detective Comics #27 in 1939, a retelling of the story by novelist Brad Meltzer and illustrator Bryan Hitch, and more.