Try a computer supply store, or maybe an industrial electrical supply store. We used a lot of multiwire 16 gauge cable for industrial applications in plants I've worked at.
Hell, for a 6' length, you might even be able to check with a supply store or even the
wire manufacturer itself, and request a 6 foot length as a free sample. (I've done that
before).
Good luck, most places I know of, won't sell in less than a 50 foot roll.
I haven't looked, anything like this on ebay?
