Costs are highly dependent on the program you choose. If you are doing a semester or year-long program, you pay tuition directly to EU as you would if you were staying on campus. All other expenses (room and board, etc.) are paid to the institution abroad. For many programs, room and board is similar to a semester living on campus.
For full-time students participating in a faculty-led program during J-term or Spring Break, tuition is included. You will pay the cost of travel in the form of a program fee, which is listed on the program brochure. Students who are part-time or are only full-time for one semester will incur additional tuition fees.