I have done a bit of looking around, and seen where you can buy some 5" and 6" plain hat pins to decorate at JoAnn's in the jewelry department.
There is another place I seen that has many in longer. They seem to be in a bulk buy, but seen some that look very interesting. I forget if we can post that here. So I will try to give the name and then type in their search 'hat pins'
It's called - firemountaingems - Lots of stuff there.