Please don't take this wrong, but I'm not sure I understand. I assume you bought a Millermatic 250 because you wanted a high quality welder. And you certainly got one. Like I said, I love my Millermatic. If you bought a Millermatic for its quality, wouldn't it make sense to buy a Miller spool gun? I don't think you'll be happy with a Chinese knockoff, works with the Millermatic 250 spool gun. I could be wrong, but I'd stick with Miller.
