One other idea you may want to look into - can you wield a soldering iron? If so, grab a 50' hank of "HDTV" (how I loathe that acronym that has already lost all meaning) coaxial (I think the rating on it's 5Hz - 2GHz and it's usually double shielded) and some strain relief ends and solder yourself up a sub cable.

Bren R.