This coin from Monaco is one of extreme value.
Look at the back of your 2-euro coins. If you can see a woman's head on it and write Monaco on it, then you can look forward to it very much. The head is the former Princess of Monaco Gracia Patricia, also known as Grace Kelly. The special coinage was created in 2007 on the occasion of the 25th anniversary of her death. It only had 20,001 copies, of which 4,000 could be bought and the rest came into the hands of collectors. The value for collectors is EUR 2.000, -
Of course, you have to be a lucky little guy, because it's hard to find such a coin. But it is not impossible - just look in your pocket, it might be worth it!