I am in a similar situation.
I had purchased 150' of "standard" Monster Cable at Menards, a regional home improvement store. Now, is it me, or is Monster Cable going out of their way to either hide, or eliminate listing of the wire gauge?
Anyway, upon reading this article, I learned that 12-14GA was recommended. This prompted me to more closely examine the spool of MC where I learned that it was 16GA.
Thus began my quest.
Home Depot - HD had 100' spools of 14GA RCA "100% oxygen free" $34 each.
Next stop Best Buy, where I found 50' spools of 12GA from Accoustic Research for $50 each. This stuff appears to be 80% casing and HUGE casing at that!
In the end, I opted for Axiom's wire. The specs were every bit as good as Monster Cable, the price per foot was less than the AR at BB, and the casing appears to be of resonable size (making it easier to pull multiple runs through conduit).
Other than the 14GA RCA, my local Home Depot only had 14GA bulk stranded electrical wire which, for some reason, looked far smaller than the RCA "100 oxygen free" "Digital" cable.
Okay, the Axiom is on order, I could have probably found other 12GA on eBay for far less, buy I have an assurance (along with a possible "illusion") of quality in that it will perform well and last a long time.
I am REALLY looking forward to hearing my Axioms for the first time. They have sat on the floor of our formal dining room, in their boxes, awaiting the day that the "Serenity Home Theater" is finished and comes on line.
"Someone tries to kill you - you kill 'em right back!" Capt. Mal Reynolds