Amazon has the 6-Pack of Scotch-Brite Non-Scratch Scrub Sponges for $5.14 with free shipping on $25+ or with Prime.

The 9-pack is $6.64 - $0.65 off coupon (check "Save an extra" box, eligible on first S&S order for this product) - 5% off with Subscribe & Save (can cancel at any time) = $5.66 with free shipping on $25+ or with Prime.