Our 20tb/m costs us $414... if you're saying that you can amortize those servers, rent the space and pay for upkeep for less than $4k a month?

We have another service that has 20x the bandwidth, but it's a legacy GAE that has super cheap premium egress... But I'm told that AWS says that their pre-pay discount will be competitive in about a year, the rate that we're growing.

The negotiated egress prices are much lower, so long as you are buying future egress. If they're not worried about you jumping ship (you use a lot of their aws-native services), you can get a great deal.