If you had fluid leaks for any period of time.Or you'r car has alot of miles on it.Then worn out clutches are no suprise.And $16 each to change them is a fair price if the mechanic is knowledgable and honest.As far as the health of you'r transmission.This is nothing more them general maintanance.Kind of like getting you'r brake pads replaced.If the job is done before any damage has been done,it's almost as good as new.But if you drive around for a long time with you'r transmission slipping and acting up.It would be like driving around with you'r brakes makeing squealing and grinding sounds for weeks before getting them fixed.If the problem is fixed early,it's an easy fix.Ignore the problem,and it only gets alot worse.If you'r not sure of the mechanics honesty.Call and ask to see the old parts after the repairs.Good clutches have grooves in them that should be at least 1/32nd inch deep.Close to that or less,and you'r mechanic is right to change them.