To answer the questions here, we currently have 16Mbps full duplex line (don't worry, no FUP there), which costs like 900$/month, but it's payed by the customers of our tiny wireless network. And because the flserver consumes mainly the upstream, it just uses the unused connectivity as our network consumes mainly the downstream.
So I don't have to pay anything extra for the connection now, I just pay for the 24/7 electricity. In August, I was worried by the exponential increase of traffic but it seems to slow down so I hope everything will be okay even without reducing the player limit.