A 100 Gbps uplink is an average of $0.03 per Mbps per month for transit. So that would be $0.00093, a tenth of a penny for a terabyte. This is not even counting peering agreements that make sending the bandwidth free, or the 95th percentile billing which makes spikes free to handle. Or that bandwidth is only charged 1 way (eg. If most of your bandwidth is sending data to consumers then sending data to your server is free).

https://resources.telegeography.com/ip-transit-price-erosion...