Most frugal websites will tell you to stop buying cereal when you have a tight grocery budget. I respectfully disagree. With a few coupons and a store sale you can get name brand cereal for well under a dollar a box.
This week our Kroger had Kellogg cereals on sale for $1.99. There were online printable coupons for several of the varieties that were $.75 off one box. Our Kroger doubles coupons up to $.99, so these coupons took off $1.50 off the $1.99 box of cereal! You can't complain about paying $.49 for cereal. In the past, I've also gotten great deals on oatmeal and Poptarts.
If you have a Kroger in your area check out Kroger Krazy. This site shows how to use coupons with Kroger's weekly sales to get the best deals. No Kroger? No problem! Check out The Krazy Coupon Lady. This site has coupon deals for 24 different stores. Chances are they cover a store near you.