Making Warcraft Gold - Worth it?

If you have a high level character it's pretty easy to do an instance run or to use mining or herbalism to make a decent amount of gold.The problem is if you only have characters below level 40. You can trade the AH for some decent gold and can probably make up to 20 gold for an hour of effort once you know what you are doing. If this is enough, that's great but what if you need 400 or 500 gold