i think music is super valuable, but when currency gets involved, our ideas of value get really different. That's ok, it just means some of us have more currency to spare for music than others.
You could pay anywhere from $65 - $100+ per hour, and meeting for 30 or 45 minutes works well, too.
If you can afford to pay more, you can help someone else who can't afford it still take lessons. That's really cool—we create community by sharing resources.
You pay what you can afford, they pay what they can afford, but everyone gets the same level of instruction. In this way, the sliding scale system can be altruistic: you obtain knowledge for yourself, provide support to me, and help provide knowledge to others.
Musicians (students and teachers alike) rely upon the support and generosity of their communities to build a sustainable life; I hope to build a community of supportive music lovers in my private lesson studio.