I will admit that I'm not sure what my options are for a $350 AR and I haven't really seen anything specific posted. Perusing the usual suspects, I don't even see it as an option. Someone mentioned PSA but they start over $500 for a basic carbine. Their cheapest kit, sans the lower is $400. I see a $229 upper at Midway and I reckon you could slap together a lower and be at $350. So it seems to me you're really scraping the bottom of the barrel with a $350 AR. Might be fine for someone who just wants to have one but not shoot it very often but I'm not convinced its something I want to stake my life on. I also have to really question the comments that there's no difference between a $350 AR and a $700 one.
I'd rather have one good one at $700 than anything you could throw together for $350, even if there were four of them.
The 300 Blackout pistol I completed before the 'rona showed up cost me $375 with an optic and a SBA4 brace.