I love your washcloth idea! I think people really respond to packaging that looks (or is) made from recycled materials.
How about using something like the net bags that veggies like onions and potatoes come in and tying it off with a pretty bow?
Or some type of origami box, like what Chinese food comes in (you'd have to buy these boxes new)?
Or cutting small pieces of wood (like pallet wood), maybe cut 3 or 4 inches square, and tying your soap on to it with some colored ribbon?
Maybe find a way to use those cute paper cups that you make cupcakes in? These paper liners are inexpensive and come in a lot of different colors and patterns. Or wrap your soaps and jars of scrub in small paper doilies with some ribbon!
I think it's most important to include your name and business contact info on a creative and eye-catching card so they remember you and can find your products in the future! Good luck!