Stamps on the theme of Esperanto can easily be found.
Coins however are less easy to obtain.
And yet, there are...
A fine example is this 1 Cuba Peso coin, to commemorate the Esperanto Congress in Havana in 1990.
It's a non-circulating commemorative coin.
Mintage is 6000 only!
Catalognumber (Krause) KM 250
Ø 30 mm
Copper - Nickel