Humble Bundle wants to help you improve your cosplay abilities. The Cosplay Like a Pro (affiliate link) bundle offers you $512 worth of cosplay books for only $18! There are titles to help with specific pieces such as horns or shoulder armor as well as books for materials like EVA foam and glue!
There are 41 books in this bundle and it appears to cover just about everything related to cosplay. There are even books to help teach you how to sew! In addition to helping you increase your cosplaying skills, each purchase supports Extra Life, “a Children’s Miracle Network Hospitals fundraising program that empowers the gaming community to make a difference in the lives of local sick and injured kids.”