If I push 1 GB per month, https://www.google.com/search?q=1GB%2Fmonth+in+mbps&oq=1GB%2...
You can assume they are not paying list rate when they buy $400M of service.
If they push ~40gbps on average, that's 13PB - https://www.google.com/search?q=40gbps+*+30+days+in+PB&oq=40...
13PB is 13M GB. 13M GB @ .08/GB = $1.04M
$1.04M/40gbps = 1.04M/40000 = $26/Mbps.
I pay less than a 10th of that outside.