Most people are in agreement that two of the most important parts for accuracy are the barrel and trigger of a firearm. As I am looking for a barrel, I wonder often what the differences mean for a 100 yard pistol or SBR.

What would one expect accuracy wise for a $300 barrel vs an $80 or $150 barrel?  

And what advantages do different finishes have over the other?  

Stainless?
parkerized?
Chrome moly?
Black nitrade?

I have seen many recommended, but I still can't sort through it all. I know the barrel is important, but I also know I am building a pistol, and I am sure there is a limit where the cost is too high and also know that there is a point where you are buying junk. In the threads where people are recommending barrels, they say they are accurate, or work well, but to what standard are we talking?  

I hope this isn't too confusing.

I dont know about cost, but my cmmg wasp melonite 8.5" will do sub moa groups with the 110 grain barnes blackout bullets. I have one of the older ones that were reported to have the wrong twist rate printed on them, and even non-concentric threads. I use mine with a suppressor with no issue, and frankly do not see the need to spend more money on a barrel. This one seems to be more accurate than the stainless one from midway that I have.