Cost to Rewire a Tonearm?

I would estimate $100-150 for the labor alone.  The cost of cable and connectors can vary all over the map.  
I replaced the Cardas wire and KLE plugs on my Analog Instruments Siggwan arm with ZavFino 1877Phono copper Litz wire.  By that time I had already replaced the KLE  Harmony plugs with KLE Absolute so I used the same Absolute plugs on the new wire.  
I thought the 1877Phono wire was a rather modest upgrade from the Cardas.  I ended up replacing it with a Discovery cable that was even better.  It’s been too long for me to recall the details but I remember especially liking the dynamics with Discovery.

With the Discovery I followed Joe Dephillips’ advice not to use a continuous run of his tonearm wire but rather have the tonearm wires hand off to his Plus 4 interconnect a few inches out of the arm.  I also used his recommended locking RCA plugs. 

salectric did you use the $20 a foot 32awg Discovery wire. Hearing the zavfino was only moderate upgrade from Cardas is making me rethink re wiring my arm with Zavfino. I don’t really use the table but I hate see it just sitting there year after year. 

@paulcreed 
I bought the Discovery cable already assembled directly from Discovery, not as raw cable.  I assume the skinny wire portion is the 32g wire sold by PCX but I don’t know for sure.  As I said, that wire only extends a few inches past the tonearm base.  At that point it is spliced to Discovery Plus 4 interconnect which goes on to the RCA plugs.  What I bought was the complete cable with 18” or so of the skinny tonearm wire at one end already connected to the Plus 4 with RCA plugs at the other end.  All I had to do was connect it to the Siggwan arm tube.

I should add that the tonearm wiring on the Siggwan is all on the outside of the arm tube.  It fits into a groove on the underside of the arm tube.  This makes swapping wires an easy task.  Literally just a few minutes.

If I remember correctly, $500.00 including Audio Note silver wire. I provided a pair of KLE Absolute Harmony on one end.

As lewm suggests buy your own wire. It is really not hard to do yourself.
You use the old wire to pull the new wire through. First disconnect the wires at both ends and make sure the old wire moves freely by gently moving back and forth just a little. Then solder the new wires to the old ones, pull the new wires through and disconnect the old wire. Finish both ends as indicated. 
If it really makes you nervous I would be happy to do it for you, no charge. Just cover the shipping.
Mike