AWS overcharges extremely for bandwidth. But yes, I'd expect that much bandwidth to cost at least around $1m on most providers. If you end up using THAT much bandwidth with so few GET requests, expect a call from CloudFlare.
>Cloudflare may, with or without notice to you and without liability of any kind, temporarily limit your storage and/or the number of requests you can make or receive using the Developer Platform for any reason (in its sole reasonable discretion), including without limitation, if processing such requests would put an undue burden on the Cloudflare network, adversely impact the Service, or otherwise threaten the integrity of Cloudflare’s networks.