Amazon has the 10-Pack of Plink 90 Garbage Disposer Cleaner & Deodorizer Spheres (Lemon) for $4.99 - 5% off with Subscribe & Save (can cancel anytime) - $1.50 off coupon (check “Save an extra” box, eligible on first S&S order for this product) = $3.24 with free shipping on $25+ or with Prime.