I will answer your question based on two (2) examples that I have fired personally. Obviously, this doesn't mean a whole lot since it is a very small sample size.
I bought a Springfield Armory "Loaded" 1911. The accuracy was terrible (along with other quality control issues). The first time I shot it, I was with another guy who had the same pistol, however he had got a deal on Barsto barrels and had one installed in the Springfield he was shooting that day. I fired about 100 rounds and was shooting groups of like 12" at 25 yards. This was the first time I had shot with this guy and he kept trying to make comments on how my accuracy would improve with practice and all that. I told him, not to be arrogant, but this isn't all me. This gun simply isn't accurate. To prove it, I took out my Colt 1911 and fired several groups that were a tiny fraction of the size I was getting with the Springfield. This caused him to change his tune. So, as an experiment, he took the Barsto barrel out of his Springfield and we put it in mine. My groups immediately shrunk to very respectable dimensions. To me, it was obvious that my Springfield had a serious barrel issue. So, I sent my Springfield to Clark's Custom Guns and had an accuracy job done on it including a new Barsto barrel. The price was no where near the numbers you mention:
http://www.clarkcustomguns.com/scdetail.htm
Obviously, it is now super accurate, however after around 100 rounds, it starts to malfunction.
A buddy of mine bought a Springfield "loaded" 1911 and had some reliability problems with it. I asked to borrow it to see if I could find the problem. The problem was obvious: the factory magazines were horrible. When using Wilson Combat mags, it ran like a top. But, IMO the accuracy was substandard. It wasn't terrible, but it was at the low end of what I would consider acceptable. For a defensive gun, it is good enough, but that is about it.