"Why wouldn't you pay more?" comments are rather annoying.
Why would you pay more if you don't have to?
Bitbucket caps their price at $200/month for unlimited users.
That would pay for only ~25 users on github.
Basically they are 9 times as expensive per user as bitbucket.
Have you considered that if you self-hosted on a repurposed desktop machine running off solar panels, with unpaid interns doing maintenance, you could cap it at $0, and save on the heating bill during winter?
