tonearm cable, do you need one?

I use a VPI phono cable with my Classic 1 which is an extension of what the arm is wired with good system synergy.

I did end up getting a couple phono cables.  The VPI phono cable and also an Audio Envy phono cable.  I like the Audio Envy better all around. The VPI is a little thinner and brighter, it's close but I'm keeping the audio envy.  I don't notice anything different with or without the ground attached so maybe you can just use an interconnect and don't need the specialized phono cable.  

The difference between phono cable and interconnect cable is SHIELD , not a ground wire. Do you understand why 99% phono cables are shielded? The signal from phono cartridge (especially MC) is much lower than line level signal from any other component. Without shielded cable you can hear a radio signal in your speakers or noise and hum when you connect it to your tonearm/turntable with MC cart.
Some interconnects are shielded, but most if them are not shielded and using them instead of phono cable is bad idea.

As for the ground wire you can use any thin wire (it will not affect sound quality) between turntable ground terminal and phonostage ground terminal if needed.