Apparently much more than I originally thought! I took these recipes from a website called Wise Bread: Living Large on a Small Budget. (I found the site when I was looking up how to live without an air conditioner this summer. We are going to experiment with that. Wish me luck!)
In Addition to this, I also found a vinegar and baking soda shampoo. Mix 1/2 cup of baking soda to 3 cups water. Only use a small amount in your hair, make sure you get it every where, then rinse with 1/2 cup of apple cider vinegar. The author said it takes about two weeks for hair to not feel too dry. Also, she said she missed the smell of her shampoo. I don't see why you can't add a few drops of your favorite E.O. to the original mixture. PS Your hair will not smell like vinegar after you rinse it out with water. I will try this when I wash my hair next time. Don't hold your breath, I only wash my hair every 10 days or so.