For a team, pricing is different. 50 repos is $100 a month, 125 repos is $200 a month ($2,400 a year). Granted, it's not "exponential", I was using a figure-of-speech referring to the pricing becoming significant.
For an internal-dev team which generates a great deal of new repos throughout the year (one-off scripts/programs for different departments, etc...), this adds up very quickly.
If you reach that 126th repo, it jumps to $450 monthly or $5,400 a year. At those prices you get questions from Accounting about why we aren't hosting this internally...
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.
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).
For an internal-dev team which generates a great deal of new repos throughout the year (one-off scripts/programs for different departments, etc...), this adds up very quickly.
If you reach that 126th repo, it jumps to $450 monthly or $5,400 a year. At those prices you get questions from Accounting about why we aren't hosting this internally...