I wish I had the website of the woman I saw on CNN. Basically the site tracks all known and unknown sales at various grocery stores along with coupons. They then have a "D-Day" that you go and purchase certain things on your predefined list. The woman on the news bit bought like $250.00 worth of groceries for around $30.00.
It also involves a lot of buying when prices are low on longer lasting items and storing them. I wish I could remember just two or three keywords from the news. At the time it seemed like a lot of work, but for savings like that I'll start clipping.
P.S. She wasn't just buying generic and already low cost items. She had about 30lbs. of t-bones in the cart when she checked out.