Sometimes a one base material sensory bin with no additives in it can be the funnest! My daughter loves her birdseed sensory bin. I gave her some of her Baby Bullet jars to use for scooping and pouring and she went to town.
Set up couldn't be easier, just pour some birdseed into sensory bin. A big bag of birdseed can sometimes be a little costly. Just remember that using it in this way is very frugal as it can be used over and over again. When we're not using ours that we use for our bins I keep it in a big Ziploc bag. Birdseed also has many other uses, like feeding birds!