Vinegar hair rinse
Believe it or not, my mom used to wash my hair with homemade lye soap. We were poor and that's all we had. But Mama also kept plenty of vinegar on hand for canning and making delicious fresh cucumber slices and onions from the garden. So she used a vinegar rinse. She worked about a tablespoon or so of vinegar into my hair and then rinsed with water. The shine was incredible on my red coil curls.
I heard of a vinegar rinse recipe where you mix up a bunch of it at once, mixing it with water and a few drops of essential oils, but for me, the way Mama did it worked just fine.
When I've run out of shampoo or in the days when we were newlyweds and committed to too many payments, I used dish-washing liquid for shampoo. It takes only a few drops--much less than conditioning shampoo, and gives a beautiful shine. If you have it, use conditioner afterward.