Yes, that is a ripoff.
The 9mm P is larger diameter than .380 and pretty strongly tapered, You can't cut it down. (Although you can make 9mm Makarov that way.)
I get the occasional .380 mixed in with "once fired" 9mm or even my own range pickup. The 9mm sizing die does not even touch it and the press handle slams to the bottom with no resistance if I do not spot the difference when I pick up a .380.