There is only one coin like this in the world, or at least only one known specimen. Citing the 'Historia numorum, a manual of Greek numismatics':
'This unique coin, now in the Brussels Cabinet (bequest of the Baron de Hirsch), is in many ways highly instructive as showing the point of development which art had attained in Sicily between B.C. 476 and 461. The scarabaei of Aetna were remarkable for their enormous size, hence the scarab as a symbol on the obverse.'
A quick web search reveals numerous replicas for sale. If cast from a non-precious base metal such as pewter, the value is near zero - perhaps a couple of US dollars to the right collector, looking to own a replica of this unique coin. If made from silver, then the value increases to about $50 or so.
This coin is notable for being one of the rarest and most precious of all ancient coins. It's comparable to the 1933 Saint-Gaudens Gold Double Eagle in modern coinage. If a second genuine specimen were to be uncovered, it would be worth hundreds of thousands, if not millions of dollars.
If you are interested in learning more about this coin, there is a great article called 'The Brussels tetradrachm of Aitna: possibly the most precious ancient coin in the world' written by François de Callataÿ. It is available for free at this link on Academia.edu.