[sls]

GitHub Enterprise is an appliance VM you run internally. It's charged per seat. The last enterprise-y company I was at used it primarily because you keep your code inside the firewall, but also because the pricing model is more aligned with the usage in that environment, as you suggest.

[Alupis]

GitHub Enterprise is even more expensive than what I quoted above. The quotes above are for private "team" repos under an "Organization" on Github (they host it all).

[brazzledazzle]

GitHub Enterprise is pretty pricey. It's almost exclusively about being able to host internally.