https://www.trainlayouts.com/about/ is in NJ (I think they are northern NJ), they do layout building. I have never used them, hopefully someone on here has experience with them. (They also are a forum Sponsor).
With some of the vendors, they work all over the country, so you don't have to limit it to firms in NJ, they will built at their site and then deliver and install it. http://twtrainworx.com/index.html is one of them as well, there is also Hikel layouts as well, too.
