I have been a big fan of the BeautyBlender sponge. I was so excited after I used this to apply my foundation. My excitement was soon dampened by the realization that to replace this would be really pricey! So I started my mission to try and find a dupe for this. I came across the 4 pc puff sponges from Bundle Monster on Amazon found here http://www.bundlemonster.com/beauty-accessories/4pc-pro-beauty-flawless-makeup-blender-foundation-puff-sponges.html
I bought the sponges with my own money and these are all my own opinions.
I didn't find them to be dupes at all but still an interesting tool. Check out my video here: