From the Barry & Darling vcoins.com store:
http://www.vcoins.com/ancient/barryanddarling/store/dynamicIndex.asp

                   
                  Gordian III and Tranquilina AE26 (5 Assaria) - Thrace, Odessus

                        Obverse· Facing busts of Gordian III and Tranquilina
                        Reverse· Serapis standing left, holding transverse 
staff.
                        Size / Weight · 24 mm / 8.95 g


                        Price 
                          US$ 30  € 24.56
                         Ł 16.67
                         AUD$ 39.70
                         CHF 38.17
                         CAD$ 35.95

                        Rates for 8/24/2005