For this money making method you will be filling baskets with fruit. This is a really easy and quick way to make money of the grand exchange. Before you start i suggest you check all the prices since the profit of doing this goes up and down.
First buy either Cooking apples or Oranges (5 for each basket). Then buy a basket. Bank the fruit and fill you inventory up with the fruit, then click on the basket to fill it up with fruit. Doing this you should be able to make a good profit, have gotten between 50 – 1000 profit per basket, and made 700k + gold in an hour.