Squire Boone (Daniel's brother) was a blacksmith by trade, and a traveling blacksmith at times - on horseback. When I asked our local 18thC expert how he did it, he said Squire carried a few tools, maybe a hammer or two and a pair of tongs. He would find a place with a fairly consistent wind and dig a narrow trench with a funneling flare on the windward end, roof it using the sod he'd removed, and build a fire at the downwind end. Find a big rock for an anvil and he was open for business. Of course, he was working with wrought iron and his work didn't have to be pretty, just functional.
That's about as cheap as you'll get, I think.