Grand Exchange: What should I Invest in?

The Grand Exchange (also abbreviated as GE) is a trading system for players to buy and sell from each other almost every tradeable item. Membersget six spaces in which they may trade items, but free players are only permitted to two. Traders don't need to advertise, meet each other, or even wait at the GE for their trades to finish. All coins and items from fully and partly finished trades are collectable at any bank, but not at bank chests (except the one in the clan wars lobby) or deposit boxes. Additionally, players will receive a message in their chatbox when the status of a trade offer is updated. This trading system resembles a real-life electronic assist exchange. Many players find it useful to sell items on the Grand Exchange rather than to a General Store, as the profit margin is much larger for useful items.


What Should I Invest in?
There are a number of quality stocks - items that frequent up and down so that profits can be made fast and easy. 


 Coal - Highly traded commodity, always needed. This is a simple no-brainer.


 Mithril Ore and up - ores are always in demand.


 Raw Lobsters are the most recommended stock for Winter 2011. Theyve slowly dropped in value over the year and are now incredibly cheap to invest in. Raw Lobsters are always in demand as they are easy fish to use to raise Cooking. They'll make a comeback in 2012, likely rising over 200gp a piece when people realize they need some food for training.