Hahaha, I had your same problem. I look at online sources and most of them cost around $100 per three months or something like that if you want them on your official Transcript. Forget online.
Here’s what I did. Back in February when my school was doing course selections, I told my Guidance Counselor that I want to get credit for AP Physics C but am unable to take it online. So they said they would be able to assign me to a teacher certified to “teach” the course, and so I would basically sit in one of his classrooms and be a one-person class. If I’m lucky, it would be during his Planning Period. If unlucky, I would have to sit in say a Chemistry Honors class and sit quietly and study. The purpose of this would be so I can have someone who can fairly grade my free response and have access to official practice exams. (although, to be honest, since AP Physics C so rarely undergoes course revisions, you could take a MC exam from the 90’s and it would still be accurate to the actual exam)
Ask one of your Assistance Principals, Guidance Counselors, and Physics teacher to find out whether this is okay.