Amazon has a few 4-pack cereals shipped for as low as $7 when you checkout using Subscribe & Save (you can cancel this at anytime within the “My Account” tab)!
Fruity Pebbles Cereal, 11-Ounce Boxes (Pack of 4) – $7.16 Shipped
Cheerios Cereal, 14-Ounce Box (Pack of 4) – $9.60 Shipped
Happy Shopping!