Seems another geocacher found the coin now on ebay:
http://www.ebay.com/itm/Pewter-SEA-SHELL-WITH-RED-GEM-Trackable-/271761436498?pt=LH_DefaultDomain_0&hash=item3f463e6f52
I will contact the seller, how it comes that he sells obviously my coin...
Strange world...
Keep you posted...