Twice on bid sites I got jobs where I was the second lowest bidder. The lowest bidder produced very shoddy work the customer sent me samples and gave me what customer info he had. I tracked everything down to an apartment complex, of course there wasn't any manufacturing going on there. They were probably packing 3rd world country sourced parts in that apartment. Another one was a house, that didn't even have a garage or basement for a shop. No big deal if someone is just running a lathe in a shed, none of these places even had a shed for a lathe. Point is if the guy is running a lathe in his shed in the USA he is over seeing his own quality. The guy in the "Mail box store" is probably getting your parts done in the cheapest shop he can find in Mexico, China or India and of course never inspecting them. Many ask for payment up front and deliver garbage, they also constantly change their screen names.