Please see my other reply about network costs. Bandwidth is a real cost that does not currently show up on the balance sheet because of Fastly's generous donations.

That said, I would love to see more organizations implement private staging repositories for their upstream package supply. This is where they can and should apply policies to protect their applications.

Developing a single multi-protocol or even multiple open source caching proxies will cost real time and money. I'd love to see more solutions here but at this stage it will take more than a few volunteers and a "PRs welcome" in the README.