Probably the same way a lot of that stuff gets funded, a rich true believer or a bunch of less-rich true believers donating. I used to live in a town where one of the largest landholders was selling off land a few acres at a time. He had a couple thousand acres (had been farmland, but the city had grown since that time and it was not that profitable as a farm) and was able to sell it at something like $25-50k/half-acre lot. Neighborhoods went up, he got money and funded a lot of missionary activities (primarily in Africa, as I understood it). You get someone like that to bankroll a radio station, they could probably set up an endowment to keep it running for quite a while. The land the station uses and towers, if owned by the station, can be rented out for more income as well.