I think it would be somewhere between extremely difficult to impossible to get a P88 from outside the US imported. It certainly wouldn't be cost effective. You'd be better off to just buy one already here. As for getting one in Germany, for a civilian to own a handgun is extremely rare. Although they manufacture many firearms, outside law enforcement & military most civilians have to go through registration, extensive training & must adhere to all kinds of rules owning one. If you're a non-citizen of Germany this probably isn't even an option either.
they get tough rules but cool toy. when my friend was in germany with the canadian army i could not go to a range because he had no suppressor on any off his gun. They are mendatory in germany because of all that noise pollution you know