I have been attending Tibetan Buddhist meditation and teachings at a monastery for several months and am enrolling in a foundation class next month. They suggested a voluntary offering to the teacher for this class, however I want to make sure I offer something appropriate. I'm also not sure if it's a "one time" thing or if something every class is suitable. I searched the web as well as the forum for this information and couldn't find anything regarding this question.
Money is the standard offering and has been since at least the time of Lord Atisha.
However, actually using the teacher's teachings and doing what they say to do is the supreme offering.
Equanimity is the ground. Love is the moisture. Compassion is the seed. Bodhicitta is the result.
-Paraphrase of Khensur Rinpoche Lobsang Tsephel citing the Guhyasamaja Tantra
"All memories and thoughts are the union of emptiness and knowing, the Mind.
Without attachment, self-liberating, like a snake in a knot.
Through the qualities of meditating in that way,
Mental obscurations are purified and the dharmakaya is attained."
-Ra Lotsawa, All-pervading Melodious Drumbeats