I will suggest you to join crash course as it will help you in many ways. By self study you may save a lot of money but you will be completely clueless about how to study, what to study, how much you should study.

By joining crash course you will be guided by the professionals about the NEET exam, tips and tricks will be provided by the faculties, you can ask your doubts, they will help you at every step. They will guide you about what to study, important topics and points and thus you will study more effeciently. As you are already in 12th that means you have very less time so you should join crash course where you will get proper guidance by the faculties ,you will learn a lot more in very less time, it will surely help and increase your chances of selection.