It look's like an ancient best bet would be to post better photos and put it on the ancient forum to get better help.
The images are blurry so a highly specific attribution cannot be rendered, but the coin's attribution is as follows: KINGS of MACEDON. Antigonos II Gonatas. 277/6-239 BC Æ unit, uncertain mint in Macedon Obverse: Helmeted head of Athena right Reverse: Pan right, erecting trophy to right Value: ~5-50 USD, depending on the sales venue and other factors. Selling to an individual I'd expect ~$20-30, with in-focus cropped images. With current blurry images, ~$5-15. CNG's sales archives (auction results). Current offerings on Vcoins ("retail" prices). Recent eBay sales.
