MKIII bulk electrical cable source needed

Let's say a fool like me wants to replace the entire electrical cables running from the hand switches to the connectors inside the light bucket.
As it turns out It's not just ordinary grey sleeving pulled over the wires.
The grey outer covering appears to be continuously extruded over the conductors to form a liquid tight cable.
This is cable, not individual conductors inside a sleeve.
Has anyone ever actually purchased bulk raw replacement cable of this type? I would like to do so.
Can anyone help?

My Mk3 has 9 wires, in two bundles, connected to the LH handlebar switch, and 6 wires, again in two bundles, connnected to the RH switch. Belden makes multi-wire cable (gray PVC sheath, just what you need) in 4,5,6, and 8 wire bundles, usually using 18-22 AWG wire. If you're using relays on your Norton, the 20 AWG will work fine. Suppliers like Allied only sell in 100ft lots ($100-$300), so you need to find a local supplier that sells by the foot. This stuff is pretty common and is even used in wiring homes for communications. Try Radio Shack, Home Depot, generic electrical supply shops. I don't believe there is anything special about the OEM cable; its just plain ol' Belden multi-wire.

very good and thank you.
I will have a look around to find a stocking dealer.
The next time the on call shop electrician comes in I will ask him about local sources too.
Thanks again.