I've got two growing boys at home, one 5 and the other 9, both with healthy appetites. I've been lucky in that both love fruit and most veggies so my grocery shopping isn't too difficult. About two years ago my wife and I tried the Atkins diet and by default the boys followed a modified version of it. I found that eliminating most of the processed carbs from my grocery list actually resulted in a cheaper shopping trip, even though we were adding more vegetables and fruits. The drop in price wasn't all due to the exclusion of pop, chips, snacks etc., but also probably due to us cutting back on the amount we ate. One other factor that helped us cut back on the grocery bill and also helped make the work-week a little less hectic is to plan out all the week's meals before shopping. This forced us to only pick up what we needed and and avoid impulse buys also helped us prep in advance.
I'm not sure if that was an answer to your question or not :)