I can't speak to the cost of unstepping the mast, it will vary from marina to marina. The last time I unstepped my mast in the middle of the season, the marina charged me $100. Going up the mast or paying $100? Easy decision.
Masts should be unstepped from time to time to carefully inspect them, maintain them, and upgrade them. If your mast hasn't been down since you bought the boat, it might be a good idea to spend the money
and drop it. Especially, since you have a fair amount of work to do on the mast.
I'm not sure why anyone who owns a production sailboat would spend money
on a rigger to tune the mast. It isn't that difficult. Spend a (very) few dollars on
Ivar Dedekam's Sail Tune and Rig Tuning guide and do it yourself. Available on Amazon.