at a pinch you could strip off the shielding from microphone cable - make sure it is high quality stuff so that the outside shielding is actually braided copper as a lot of the cheap stuff is just lose wires twirled around to made a half-arsed shield, this is useless for pinball braid and it's also next to useless for microphone cable. 
Ive tried to get this so many times.. need some for a valve amp that requires good grounding to stop any ringing... all i can find has aluminium braid which is absolutely friggin useless as you cant solder!
