Here is an example of a commemorative from 400BC, a silver stater of Elis. The picture and description comes from Heritage World Coin Auctions, Long Beach Signature Sale 3015.
Olympia, located in the precinct of Elis in the western Peloponnesus, was less of a city than a religious sanctuary dedicated to Zeus where the all-important Olympic Games were held. The games commenced in 776 BC and continued uninterrupted at four-year intervals until AD 394, when they were abolished by the Emperor Theodosius as being too 'pagan' in spirit. From about 600 BC, the site of Olympia was embellished with temples, shrines, treasuries and athletic stadiums financed by the cities of Greece and individual Greek leaders.
Between games, the site was maintained by a skeleton crew of priests and acolytes, but during the games huge crowds, numbering up to 50,000 spectators, converged on Olympia to witness the contests and cheer on their local champions.
Starting about 470 BC, Olympic coins were struck during the games to provide attendees with currency for the local markets, and to provide income for the shrine (a small fee was charged for changing other civic coinages into Olympic coin). Each coin type thus became a keepsake of the games in which they were issued, much as modern commemorative currency is tied to specific events.
After 420 BC, two mints were active -- a "Zeus" mint striking coins with images of Zeus and his avatar, the eagle, and a "Hera" mint striking coins with imagery of, and associated with, his wife. This piece, struck by the Hera mint, portrays the goddess wearing her distinctive decorated headdress. It was issued for the 95th Olympiad, in 400 BC.