Pretty outrageous
I've paid legitimate custom shops less than half that for the same amount of work. And the installs were cleaner than I could have imagined (well, the first time at least). My aim is replicate their work when I DIY, that's how good they were.
There's also a forum member (I think in MD - his forum name is bigaudiofanat) that does this kind of stuff exclusively. He even travels to the west coast to do multiple installs coordinated beforehand specifically for his trip. I've considered trying to coordinate some people that need installs and paying for his plane ticket down to Texas.