Wow, what a neat coin. Look at the one in our picture. It comes from Munzenhandlung Brom in Berlin. At the time of this writing it is on sale for 195 euros, about $265 US dollars. Brom is a member of the Meunzauktion Online Coin Shops, a well-respected, large-scale dealer in Europe. The $265 figure is a good retail price for this old and rare coin.
From your description, it sounds like your specimen is more worn than Brom's. Here are some typical catalog values:
worn: $80 US dollars approximate catalog value
average circulated: $200
well preserved: $300
DO NOT CLEAN YOUR COIN. CLEANING RUINS VALUE.
If you were to sell your coin to Brom or another honest dealer, figure a buy-sell margin approaching 100 percent. The mark-up keeps the dealer in business.
CoinQuest thanks Munzenhandlung Brom for use of their coin photo.
Here is more information on this coin, received from Kamil Lamm who lives in Poland:
Hi! I stumbled upon Your site, as I was searching for info about a coin on an internet auction. Then i saw the coin on this page. It's not a German coin, it's Polish (Prussia was at this time a part of Poland). The crosses on the shield are the crest of the city Elbląg (germ.: Elbing). The inscription: gross ar[gente] triplex civi Elbing = silver triple grossus of city Elbląg. On the other side: III (denomination); Sigis[mund] I Rex Polonie Do. [minus] Tocius Prussie = Sigismund I (the Old - polish: Zygmunt I Stary) King of Poland, Ruler of whole Prussia. Regards, Kamil Lamm.