Rare 20 cent coins - special mismintings bring 825 times their value. Some 1 euro coins can also fetch thousands of euros - as can certain 50 cent coins.
Anyone who discovers an incorrect embossing can try their luck as a private seller on the Internet - and use the prices of other offers as a guide. It is sometimes possible to earn large sums for particularly rare coins. By selling rare D-Marks, you can be sure that you are not buying a counterfeit coin.