I used to be able to easily do some crazy coming stuff, and not just processed crap, but milk, nuts, household goods, etc. Once I got a decent stash, and the show made stores start changing their rules, it got harder.
Now, I check the ads for the stores we have (Fred Meyer and Safeway) and download their digital coupons. FM will send me coins every quarter for things I tend to buy. They'll do $2 off $10 produce purchase, or $2 off in the meat department, stuff like that. They also send a reward coupon for an amount based on prior spending, which is good for most anything.
This week, Safeway has a milk coupon, $1.99/gallon, limit two. I use the digital coupon, and grab a couple ads (they keep them by the front door) do that I can use the coupons from there on a later trip. I make a latte for myself every day, and my son likes milk, so we use quite a bit. Between the coupons and sales to get milk for the same price at FM, I can usually keep it stocked without paying full price.