Keep in mind steel rims are a core welded into a rim, so yeah there has always been places that will widen rims, though it's fallen out of fashion in modern years.
Primary way to widen rims, was always to source blank rims of greater width, or find cheap rims off something that came with wide rims, then grind out the welds on the core/hub, weld in new, done with care the result is perfect.
For what it's worth, there was a place in Brisbane that used to do heaps, and I remember most were like $50 per wheel, but that was ages ago, I don't think the places is still there, and the work for this type of thing has gone through the roof.
