I don't know how everybody does it, but around here you can rent time at a professional grade forge. Sort of like how people in the city rent small plots of land to grow plants which is usually run by parks and recreation or some other local agency. But don't under-estimate somebody having their own forge in the backyard.

Talk to anybody who is into woodworking and the conversation will eventually turn to their plans are to build a workshop that would easily be more costly in terms of time, money, and space than any forge could be. I wouldn't doubt that many guys have a their own "hobby forge."