Regarding the original post...my method is to shop around the perimeter of the store as much as possible and only venture into the aisles for food I don't make. Like bread products, cheerios, and sigh-canned tomatoes. It'll be a great day in my family food-wise when I finally learn to bake! This method is a bit simplistic but it generally gets the job done.
And re: the canned tomatoes which have been a staple in my family's diet for awhile...we're looking forward to our tomato harvest this summer...hopefully it'll be a bumper yr and we can jar our little crop in place of the grocery store cans. If we have no luck with our own garden (we're not the best gardeners (yet!)) I'm going to buy from a farmers market and use those to jar.