Cost to Rewire a Tonearm?

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

Rewiring a tonearm is not child's play but close. They are not complicated devices. It is difficult to believe so many audiophiles are uncomfortable with a task like this.