Difficulty: Medium
Money Needed: 250,000gp or more.

A good way to make profits of around 100-200k very easily is to merchant death runes. Varrock is a good place to start this. Go to the runes shop (located on the map with an icon like this: ) in an empty world.

Now start buying death runes like crazy. Keep swapping worlds if the shop runs out. A good tip for this is to buy over 1k deaths to make the larger profits of money (recommended)

Now that you have over 1k of deaths (recommended), it's time to swap to world 1, making sure that you are still in varrock. Now head over to the west bank once you've loaded the world and start selling the deaths you bought for 280- 300 each. Don't go lower or you will not benefit from the larger profits.

As you may have noticed after selling the deaths, you've become a lot richer than before. Enjoy the extra cash!

This is one of the prime ways to make a lot of easy and quick money and can also be used in the same way on chaos runes. Just follow the same order (although you will get less of a profit by using chaos).