U-1017 cap badge + bierzeitung

[IJSBEER]

Recently purchased this cap device at an online militaria shop:

[IJSBEER]

Since I paid €650 for it my question would now actually be how much this badge + bierzeitung is actually worth at this very moment. Could anyone here tell me how rare these cap badges are anyhow, provided this one is authentic, but it stood model for the one in the Book "U-Boat Emblems of World II 1939-1945" by Georg Högel. Does that raise the nominal value significantly?

Edited December 22, 2018 by IJSBEER