Who do I ask about tuition costs for study abroad?

Should I ask the Office of Study Abroad or the instructors of the course or someone else?

Who do I ask about tuition costs for study abroad?
If you're studying through a program of your home university, then ask the study abroad office. If you're applying to a school overseas directly, then ask their registrar office (or their visiting students office). Check the website, they should list fees for overseas students.