Hi Stephane
the cost of a Sturtzhelm was very expensive, early models buyed by the owners dont have any insignia or the SA cap eagle.
Later the helmet was buyed by units (Sturm, Staffel, Motorstandarte...) at the Reichskassenverwaltung NSKK, as well insignias.
The 1939 eagle came too late, they was other things to buy for the german war machine.
Cheers