Cut the jacket and shielding off and strip out the lining.
It's kind of a nuisance but the added effort wins you high-quality wire for between ten and twenty-five cents a foot.
Alternately you can get wire from BTG; it's more or less the wire in Mogami W2893. $0.80/ft, but you don't have to cut any jackets or shields to get at it. I think the added price is fair, considering.
These prices I'm throwing around assume that you're in the U.S.