I brought my dress to the Sewing Room and had a lot that needed to be done: a bustle, hem brought up, and the dress taken in, plus I needed straps added from the fabric on the train. I also needed alterations for the flower girl dress. The price was very reasonable and I paid what I was quoted.
I had to come back to the shop 3 times to get everything right, which seemed reasonable to me. Little things were fixed right away (like a strap that was accidentally sewn on backwards!) and without issue. However, I had inquired about my bustle not being strong enough to withstand a night of dancing and was assured multiple times that it would stay. It did not. In fact, the bustle broke within an hour of the reception. I ended up having to use the loop on the inside of the train (for hanging and storage purposes) to hold it up all night long.
The straps were beautiful though, and exactly what I wanted. I would only suggest having them use more than one hook if your dress is heavy or with lots of beading.