I will also agree that shops need to make money to stay open and make a decent living out of it.
But looking at the price differential between a Benz dealer ($90.00/hour in our neck of the woods) and $45.00/per hour for my independant mechanic (who worked for 15 years at a MBenz dealership) make me very hesitant to visit the dealer. Sure, they have a nice clean waiting room with free coffee, lavish building and uniformed employees. They can also brag about having the cleanest shop floor short of the local hospital. All that costs money for which I am not ready to pay for. What I want when I get my car to the shop is competent repair and fair price done by someone who knows what he is doing. If it takes 4 hours, he'll charge me for 4 hours, even if the book says it should be 6 hours. If it takes 8 hours, he'll charge me for 8 hours, and that's allright with me. I like to pay what it actually costs, including a fair profit margin.