The best business model in the world: Sell something that you get for free! There is no better business model.
There is a lady that makes $40,000 a year selling tumbleweed. Yes, tumbleweed. She goes in her back yard (somewhere in kansas) picks up the tumbleweed and sells it. Its true. Our OFCG can check me on that one... or you can click here.
So, go out in your backyard (if you have one) and look for something that you can get for free. Options of things you can get for free: grass, dirt, acorns, squirrels, air, rocks, branches, pine cones. Collect the free items and sell them online. Easy!