Hello Steve,
I would recommend the following site:
http://www.return2style.de/homepage.htm
You can find many infos about the all-day-culture from the 20s to the 40s. These include some examples of popular music from that era. If you are looking for CDs with German music from the war time you may search at some online book-stores for music by the following interprets:
Marika Roekk, Zarah Leander, Johannes Heesters, Hans Albers, Heinz Ruehmann, Ilse Werner, Rosita Serrano or Evelyn Kuennecke.
Well known German dance orchestras of that period were those of:
Michael Jary, Kurt Widmann, Adolf Steimel, Kurt Hohenberger, Lutz Templin, Erhard Bauschke or 'Das Deutsche Tanz- und Unterhaltungsorchester'.
Regards