Hi Andrea ---

The coin in my picture sold for $412 US dollars during a 2021 auction. Your coin is in worse condition, so its value is less, maybe $150 to $200. 

Here is the description of my coin from the auction catalog. Be sure your coin has the same characteristics:

Leu Numismatik AG > Web Auction 18    Auction date: 18 December 2021
Lot number: 1548

Price realized: 380 CHF   (Approx. 412 USD / 365 EUR / 311 GBP)  
Lot description:

SELEUKID KINGS OF SYRIA. Demetrios II Nikator, second reign, 129-126/5 BC. Tetradrachm (Silver, 27 mm, 14.11 g, 12 h), Tyre, SE 185 = 128/7. Diademed and draped bust of Demetrios II to right. Rev. ΒΑΣΙΛΕΩΣ ΔΗΜΗΤΡΙΟΥ Eagle standing left on prow, wings closed and with palm frond behind; to left, A / PE above club surmounted by monogram; to right, AΣ / EΠΡ. SC 2195.2. Nicely toned. Very fine.
From the collections of J.B. Haarhuis and Dr. R. Friedinger Pranter, Lanz 158, 5 June 2014, 323 and ex Lanz 155, 10 December 2012, 318.

Starting price: 100 CHF