Cost to Rewire a Tonearm?

It depends on the tonearm, but $100-150 should be enough for the job.

I would say it also depends on what litz wire is used? Kondo litz wire could costs $$$$$

If you pay someone else to do it, you are also likely to be paying a premium for the wire itself.  The Audionote silver litz wire alone, for one example, may cost you more than Chakster's estimate for the whole job including labor, if the tech acquires the wire for you.  My advice is to select and purchase your own wire and present it, along with your tonearm, to whoever does the work for you. You'll probably save a bit that way.