“Day 54: This is a 2 note set issued in Summer 1921 by the Spa-Hotel "Stadt Hamburg" in the city of Büsum. The denominations included in the set are 50 Pf and 100 Pf.
The catalog value for this complete set of 2 notes is around $25 - $30. There is a more scarce variety without serial numbers with a catalog value of $60-$75. Here you can find more info about this set and others.”