I know you're asking specifically about the BCM barrel, but if you're trying to keep it close to the A1 configuration, Green Mountain sells a pretty good 20" A1 contour barrel for about $180 shipped.
http://www.gmriflebarrel.com/militarysur...twist-20-barrel (note that their website ALWAYS says out of stock for this item)
My experience with the barrel has been good; it shoots milsurp ammo to milsurp specs and commercial ammo to commercial specs. The barrel is completely mil spec, comes with the feed ramps in the extension and I think the parkerizing and chrome plating are well done. I will say that while it's easy to get someone on the phone at Green Mountain, their customer service can sometimes leave something to be desired if you have questions and I have some personal doubts about how well organized that shop is. Apart from that I think they make a good to very good product at a great value.
Also, at one time Fulton Armory sold A1 stripped uppers and used GI A1 buttstocks and butt plates at a great price. I haven't looked at their site in a while so I don't know if that's still the case.