Bait and switch
I bought a water heater from Home Depot and got them to install it for roughly $350.
When the plumber showed up, he told me that the expansion tank was too small and needed to be replaced. I called him out on that one so he went outside to talk to his dispatcher.
While the bulgarian guy was outside, I ran the numbers on the expansion tank's manufacturers website and sure enough, the expansion tank was the correct tank for this application.
Just to entertain their scam, I went on the Home Depot website and found a tank with twice the capacity of the one I had for roughly $50.
Changing an expansion tank takes less than ten minutes, upon draining the system, which you had to do anyways to replace the heater, you screw it off and screw it back on, like a lightbulb. There are a couple of small steps inbetween, but ten minutes, tops!
The bulgairan comes back and tells me that to replace the tank, it would cost roughly $260.00.
I asked him what the parts and labor breakdown was, he said that the price is $260. I called his boss and was told that they would not complete the job unless I did this. I asked for the parts and labor breakdown and he refused to tell me.
My guess is that their labor rate is well over $1,000/hour.
I told the fella to go pound sand and sent his plumber packing.