I am not a member of the fan club, so I can only provide the information included in Andreas Luketa's Musical-Jahrbuch 1998; please don't ask me for any other details, as I won't be able to provide any!
Contact address, Germany:
Stefanie Büsch
Augsburgerstrasse 14/30
80337 München
Contact address, Austria:
Doris Hager
Rustenschacherallee 28/1/2
A-1020 Wien
The club was formed in 1993 and has about 500 members. Membership is 44DM or 150 öS a year; I have no idea what it would be for people outside of Germany or Austria. Included is an apparantly quite professional-looking newsletter/magazine/whatever.
The club's Web site (German only) can be found at http://www.iukc.de/.