Some ladies use make-up sponges to apply foundation to their faces each morning. They usually cost about $2.00 for a 30-pack. They are disposable and meant to be trashed after each use. Save the money, and don't use them. Use your fingers to apply your make-up.
If you insist in the seamless look by using the make-up sponges, consider washing them and reusing them. This is what I do. I place my used ones in a lingerie bag and wash them with my laundry. They come out looking brand new!