100$ for a year? That's pretty hefty although I've been to countries that were even worse. Over here its about 15$ for a small license and 40$ for a license to fish with multiple rods (for a year in about 95% of all the rivers, lakes etc. in the country) I know Germany is stupid expensive so all those guys come here to fish Carp.
In the summer when it's hot you've got to change your tactics to catch fish. Depending on conditions fish will float to the surface or lay on the bottom so you know where to find them. On really hot days i go carp fishing with breadcrust, it's oldschool but still does the trick.