Testers are cheap because stores can buy them very very cheap from the manufacturers (unlike the actual retail box). They are meant for people to try the scent out before they buy. Those stores can't sell them either to customers. However quite often, stores buy too many testers and remove the actual item from the shelves so they are left with lots of white boxed unsellable frags so they sell them to overstock/online stores. I am not sure if online stores are able to buy testers directly to the manufacturers to sell or if they have to get them from brick and mortar stores.