What are valuable German coins?

Answer 1

That's a very difficult question to answer because there are so many varieties of German coins. Germany was not a fully united country until the 1870s and many of the individual states continued to issue their own coins until the 1920s, so you can have several different coins with the same denomination and year but different issuing states. Even after full currency unification, Germany maintained at least a half-dozen mints so you have to know which ones had low production figures in which years. Finally, Germany's very checkered and shameful* past caused a lot of coins to be withdrawn, melted, or hoarded so values don't necessarily correspond to production figures.

I've found the site www.sammler.com to be very valuable; it lists prices for nearly every German coin minted in the last couple of centuries. However, a large number of its pages are available only in German so if you don't read the language you'll have to slog through with a dictionary.

(*) Please do not tag me as anti-German - in fact my wife's family is German - but the reality of history cannot be ignored or denied.