I am trying to make my own :-) I bought plain black flags and bright orange ripstop material. I wanted to have it ready at Charlotte, but my first attempt was using neon paint - but it didn't work on the fabric I have.
@Karen, I made my own 7 flag it went great. (on a 1957 singer) However in doing so I found that a couple small embroidery ladies in the area would have made me what I wanted pretty cheap. Never forget the small private pros that hide in the tiny shops.