I can't speak to what the minimums might be, but I can speak as a part donor to friends' rides. The society does great work, I'm sure. But they were, to put it mildly, obnoxious to those who had donated. They called repeatedly, hung up on our voicemail and were quite rude when we were finally home to answer and chose not to donate again. I feel like if I donate to anyone again, I will subject myself to another round of their fundraising - and I'm not in a hurry to do that.