Ladies, this is an area where you have an advantage over men; you're much less likely to run out of a material that you could be earning money for. Your hair has a material value, and right now you're leaving it laying around on the floor of your hairdressers. Hair extensions have never been more popular, and wigs are expected to be much more realistic than they used to be. There's a constant demand for real human hair.
If you have an unusual color, thickness or type of hair, it might be even more valuable, but all it really needs to be is clean. People who buy hair extensions want the hair to be strong and natural looking so it blends in with their own. The best thing about this method of making money is that you'll probably never run out of your supply. So long as you can keep growing it, you can keep selling it!