That´s right, there´re lots of different sources "lying around" in the Gelnika Plane, not to mention the Magic Sources!
Simply Morph them, my friend (Demi3 RULES at this point!)
However, right now I personally stick to the Power Sources ("Heavy Tank", Gongaga Reactor - 100% encounter rate!) and Guard Sources ("Spirals", close to Mideel - about 80% encounter rate), since they are the easiest ones to obtain.