You might be interested to know how much it costs to run a project like GNU Guix. Well our goal is €15,000 ($17,500) a year of donations to pay for our *current expenses*.
We have all the normal expenses that a Free Software project has for our development infrastructure, hosting and that sort of thing.
There are some unique parts of being a package manager and Linux distribution that make our needs a bit more acute ...
(see pt 2)