I have recently been looking for a good dupe for the Beauty Blender sponge, and came across this one by Real Techniques. The Miracle Complexion Sponge is the closet dupe to the $20+ Beauty Blender. I picked it, because of reviews stating that it had the same "spongey" texture as the BB and doubled in size when wet. I purchased the 2-pack on Amazon [linked here] for about $10. Let us see what I think of it.
The Miracle Complexion Sponge is an orange, oblong makeup sponge with various sides to it. It has a flat edge, a pointed tip and it's sides. I love the different sides, it adds real versatility to the sponge. A major selling point for me, is whether the sponge would increase in size once wet. I ran this one under running water for a few seconds and, once saturated, grew to almost 2x it's original size. While damp, it also became more spongey and soft.
 When using this with my foundation, I notice that it sheers down the application. I also find that it soaks up A LOT of product, meaning that you'll waste more product than you apply on your face. I do not have the original BB so I cannot say if it does the aforementioned things as well.