That is the sign Gulf used at the end of a Marina fuel dock. Probably worth $300.00 but due to the size, it would be a bear to ship and cost almost as much as the sign. Too bad it isn't the 3ft X 3ft one.
I got four signs yesterday 3 Gulf 1 3' Texaco button 1 Gulfport 4x5 1 Gulf 3x3 1 Gulf button i dont know the value of any but Gulfport I thought was rarer to find as only marinas would have them.