I came across a very narrow, 5 story store in Japan, a bit off the beaten path in Akihabara, selling exclusively N scale model trains. They had a floor or two dedicated just to the models, another one for scenery, and at least one just for repair parts for your trains. It was really cool to get to see a store that was pretty clearly a passion project for the owner(s) apparently doing well, and filling quite the niche in the hobby (I imagine)