Does a 10-day Vipassana course at Dhamma Giri cost anything?

There's no charge for the teaching, food or lodging. Donations are accepted only from people who have completed a 10-day course. Applications are online only (schedule.vridhamma.org/courses/giri), and many courses fill up. Plan for 12 nights including arrival and departure days, and don't travel until you're confirmed, because only confirmed students and servers may enter.