I would like a non-profit that just pays back the spare money even more. I do not know how this would work with regulations. I guess in Germany this could be done through a "Genossenschaft", which Wikipedia tells me has an US equivalent called co-op. Would this actually work?
Edit: Realized that you could just grant discounts as there cannot be a profit anyway. Would be awesome to see several companies with the same model, first competing on prices and ultimately the percentage of the fixed fee.