From the Nemesis vcoins.com store:
http://www.vcoins.com/ancient/nemesis/store/dynamicIndex.asp
  
 Gordian III & Tranquillina AE ODESSOS OBVERSE: Confronting bust of Gordin and Tranquillina
 REVERSE: Tyche standing left, holding rudder and cornucopiae
 27mm - 12.5 grams

       Price 
         US$ 22  € 18.01
        £ 12.22
        AUD$ 29.12
        CHF 27.99
        CAD$ 26.36