Where are you from? I just had a jacket taken in on the sides and the sleeves shortened and it was 30.
I'm from the Greater Toronto Area.
He quoted what? To do what? $42 is reasonable, but expensive. Worth every penny for a good job. I have no idea what your trying to achieve with your second sentence. Are you trying to narrow the shoulders? $55 is too cheap for that service.
The back of the jacket is loose, so he'd be taking in the fabric from the side seams in order to reduce the fabric in the upper back. He charges an extra $55 to take in the portion above the armpit and below the shoulder seams, in addition to the $42 to take the sides in from the hem to the armpit. He won't be narrowing the shoulders.