I agree % is the internationally known, however it doesn't represent discount. Do you have any other smbols you can think of?
I didn't realize that I made a public comment about using camera and somebody else can't use it. Even if it was designed differently, another designer cannot use it?
However, I notice even one designer used the "price tag" shape, other designers still used it. What if you use the camera differently? E.g. instant photo camera with the polaroid coming out or any other ideas you have