Learn how to braze, buy a wire bender, drill press, table vise and scroll saw. Convince yourself that the first horn cost $800 and the rest are free.
Same logic you used to get the wife to let you buy a fishing boat.
Ken
To be picky, you only need a wire bender, hacksaw, files, hand drill, and a torch - i.e. hand tools. That's how I do mine and they are fine that way. You can do precision work with hand tools, you just have to be careful. Hack out the upright with a hacksaw, file to shape, drill holes. Get some wire, get some silver braze, braze with propane torch. And, most of that stuff, anyone would already have. By far the trickiest part is bending the cross-bar, the later K&S bender, or the "vise with a notch in it" method are fine for that.
It's not like you have to produce a bunch of them. If someone wants to build a bunch, then, yes, machine tools (particularly a CNC milling machine to cut uprights by the dozen), you could probably knock out 100 of them in an afternoon - which would be about the world's demand for the next 10 years.
Brett