Initially I purchased my gaming supplies via mail. I started gaming while stationed in Erlangen, Germany. I never found any local gaming stores. I purchased my graph paper from a local engineering supply. I used millimeter graph paper 280 mm by 380 mm. I used 1 mm equal 1 foot scale. I made the walls one foot thick.
After leaving the military, I remember a gaming store in Salt Lake City. However, I still used mail order for most of my gaming supplies. My preference for mail order goes back to junior high school. The selection of science fiction books was always limited in the local stores. I started ordering books directly from the publisher. I did the same thing with model rockets. With gaming, I just continued the trend. Today, I use Amazon.