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. 

@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.