It came with the house when I bouht it. The owner had some equipment in the shop he used. I used it for a while since I had acess to some industrial welding machines. I got a deal through the local power co-op since a good friend of mine his wife works there and her job is to deal with that and configure what a company needs for power and such. If I hadn't the minimum payment amount per month would be overwhelmingly too expensive. I paid the guy that takes care of all that at one of the shops I do work for to take care of it. I'll do anything around a house/shop but I hire or get someone that knows it well to t ake care of it.
You can use rotary phase convertors to avoid using 3 phase. I do know if you have 3 phase buying used equipment like mills, lathes, and welding machines is much much cheaper to buy 3 phase if you can manage. Lot of people looking for something nice and used that isn't 3 phase, 3 phase is out there used everywhere. I switched to rotary phase convertors for my mill and lathe and have no use for it for a welding machine. If I can't weld it I take it to one of the shops I do work for.