For the DIYer,
Belden 1800F is a nice low-priced wire for balanced cable construction (about $1.20 per foot). 24 AWG stranded copper twisted pair, tinned copper braid shield.
110 ohm impedance; .18 uH/ft inductance; conductor to conductor capacitance of 12 pF/ft.
Add a pair Neutrik gold- or silver-plated XLRs and you have a basic long balanced interconnect. BJ Cables uses it.
Belden 89207 is another choice ($4.25 per foot).
Furutech FA-220, a twisted pair with shield used in I believe the Evo II (or similar in construction anyway), is available in bulk as well (about $20 per foot -- PCOCC copper).
My fave is Neotech NEI-3001, normally at $20 per foot, Soniccraft has it at 20% off. I'd love to see the capacitance specs on it.
Good times.
David