Have you ever heard of the Color Switch?
I never even heard of this product before I came across the DIY way to avoid buying it, lol! Basically, it's some material in a tin that you can rub your brush on between colors (rather than on a washcloth or something) to pull out the left over eyeshadow so you can apply & blend cleanly!
A popular DIY way to do this is to use a hair donut instead!
And according to those who have tried it, it really works! Since the Color Switch is like $18 USD and you can get hair donuts at the Dollar Tree, it's a great way to avoid spending so much on something so, well, simple! Just like the beauty blender, it's all in the marketing, so try to avoid spending the money if you can!
If you like the convenience of a tin, you can just find the same material as a hair donut and cut it to fit a container! Voila!