I wish somebody would have told me that. I think our school district paid for students AP exams if they were enrolled in the class, so I didn't even know there was an option to pay on your own.
In my brother's case the AP English teacher was horrible. So he dropped the class and paid out of pocket to take the exam. The AP teacher happened to be the proctor and she was pissed the day he showed up. Having activist parents makes a world of difference. shrug