The best answer is that it is highly variable from school to school and even from student to student. Some schools will charge you as a student there regular patient fee🙁 , while some schools will charge just a materials fee(i.e. bracket plus wire overhead costs)😎 , while other schools may not charge you anything whatsoever(especially if you have a known interest in ortho and/or you're an "ortho clinical groupie")😀
Most schools will hit you up for a little cash though, although you'll likely be able to help work-up your case for some ortho credit towards graduation requirements.