Actually if you don't want 100% correct I have tons of brown 12' extension cords from my local thrift ($1 apiece)
I've been hoovering them up so that whenever I pass on a receiver or amplifier I can include some nice speaker wires with them. Sadly, a thrift store 16AWG extension cord with the ends cut off is way better speaker wire than what is actually sold for the purpose, and cheaper too ("speaker wire" at your local hardware store tends to be CCA not copper, and equivalent lamp cord is $1 a foot or more)
I'm going to be in the same situation whenever I go to restore the X-101-B however, the original cord has been cut to insert a toggle switch. I may just shorten it rather than try to find a replacement.