I love my main mechanic, charges $35 an hour and even picks up / drops off my cars. He even does great body work and paint. He isn't certified but is legit and can build a car from the ground up. I don't take some vehicles there that are too "advanced", he's more of a classics guy.
My BMW does get taken to an Indy shop and they charge $90 per hour, honestly I don't see much of a difference besides a nicer building and they have the required computers. Not too busy, only a day or so wait.
One of my other cars goes to another Indy shop (VW TDI) that charges $90 per hour and I wouldn't go anywhere else, top notch, they Always have a minimum 2 week wait. So lucrative for them it is!
When you have 10 cars you have to find the best people and deals for the task at hand...or get rid of the cars
I see plenty of places come and go, all comes down to the job you do, don't even think price matters all that much. I charge on the high end with my companies and we turn work away non stop.