I would want to know exactly what the $500 is for and how much of it is labor. I want to find someone to clean and check my QDII, and all I have close by is a shop that will take the machine for an unspecified time and have a technician that I will never meet work on it "when he can get to it." My being there is absolutely verboten. It's like the great Oz. And as long as stuff is mysterious and behind the curtain, it's easy to quote a price.
I'll bet there's another solution for yours.
hugs,
Charlotte