From the voters who fund them, at least that's how it's done here. Usually starts with a proposal to fund a police force, station, jail, etc., whatever the community feels they need, it grows from there as the population grows, salary funding usually isn't voted on, maybe there's some percentage figured based on a communities tax base. If it's needed money for a larger building, jail, etc., they usually go to the taxpayers through another proposal for a mileage request. If the voters turn them down, they have to look elsewhere for the funding.