In the Buddhist philosophy, teachings are given without charge as they are considered immaterial. We also practice dana, or generosity, by making monetary offerings. Dana is not payment for a service, it is given from one's own volition. This generosity is a gift that supports the teachers, the larger Yoga Dharma community, and one's own practice.
In this way, both teachers and practitioners can develop their own generosity and inclination to give without any expectation of anything in return.
Dana is one of the seven treasures for meritious action in Buddhism, and the first of the ten paramis (the gradual training for one to to develop Buddha nature).
Dana may be given online or at the Shala.