This is how merchanters make money. They sell items, price drops, everyone sells because they don't want to lose money. When everyone has their items in the GE, the merchanters buy the item in such large amounts that the item sky-rockets and everyone loses money. Well, at least this is true for clan merchanting. By not selling an item when it goes down, you'll make it harder for others to merchant and not get caught in the waves. As for your sara sword, keep it. It goes up and down so much that it's hard to tell its true value. If you use it still, just leave it in your bank. It's not worth wasting money selling it at lowest and buying it back later when it can't be bought at max.