There are also art shops near Yantai No.1 Middle and South District.
There used to be a shop opposite Xinhua Bookstore on Ma Bei Road. I haven't been there for a long time. There's one over there, but it's expensive.
And many Xinhua bookstores used to sell them.
Also, if you are out of town, go to a nearby high school and ask if there are any art students. They will tell you about the art shops nearby. There must be.