As a manufacturer of stainless steel brewing vessels, I think I can add some insight here.
Concord pots are cheap because the factory doesn't have high standards. I met the factory manager at a trade show back when we were first getting started. We considered working with them, but ultimately chose a different supplier for various reasons. I'm glad we did.
I've also met the manufacturers for Bayou Classic and SS Brewtech. Both of these factories have high quality standards, as I imagine the manufacturer of Bru-Gear does as well. I would be happy to have our vessels manufactured at any of those factories. They are all high quality companies. (And believe me, they are not made by the same manufacturer under different brands.) They are different locations with whole different production quantities and processes.
We ultimately settled on our current supplier because they wanted to compete with these other factories, and they gave us a great deal while maintaining high quality control standards.
To sum it up, how often do people complain about Bayou Classic pots developing rust? Their pots are made with type 410. (I know because I asked the manufacturer why their pots are magnetic.) 410 has the least corrosion resistance among the types listed above, and if it made that big of a difference, you would be hearing complaints about it all the time. But the manufacturer does a good job with quality control, so issues are rare.