Market like the Weather

We got the news of raw materials cost is rising. It was falling down for about three months. The marketing is floating also during the time. Some times fall down RMB50, 100RMB or 200RMB one day. Alittle rising. And then falling. Everyboday wants to buy the goods before it is rising. When is the best time for buying? When is it blooming? It is really a puzzle.