Shipping box sizes..............?

does anyone know where i can get a box thats about 30'' long by about 15'' wide and 5'' tall about i am looking for a box like this to ship a rc boat and everywhere i look i cant find that stuff :( any ways the boat is about 28'' long by 9'' wide and 3-4'' tall and it needs room for the remote control, charger, and battery. please help me!