I was looking for shirting fabric and was told it was white or off white with a small print on it. I looked in 2 different shops and one didn't have it and the other had a couple. It seems to be hard to find. I thought that I would look at the Salvation Army Store. They had lots of shirts, but they were $4.99 each. Thought they were kinda expensive. Then thinking about it--did I really want to use shirts that were worn? I decided to go with white on white and ecru prints. I needed 9 yards of assorted fabrics. The difference is, I knew what the quilt looked like. I would ask at the shop where you are taking the class. They should have the fabric.
Sue