Shaving cream provides a great medium for using touch and smell, and occasionally taste, although most who've done it say it's not pleasant. This is an easy activity to do. All that is required is a flat surface, a pile of shaving cream and a shirt or smock to protect clothes. If you really want limit the mess, playing with shaving cream in the bathtub gives you a pretty contained area and then everything can just be washed down the drain.
I use the cheapest shaving cream I can find. I have a few cans that my husband didn't care for, so I rescued them from the trash. Total cost of this activity... free!