Combating the Lie of "I can't afford to buy healthy food!"

As a teacher, I see the whole childhood obesity epidemic first hand.  It is a problem, a big problem...and honestly, I am probably contributing to it with occasional candy and treats to my students and plenty of sugar is being consumed in our house.  However, I believe there is a problem and I attempt to feed my children a moderate diet that includes as much "good for you" stuff I can afford (and they are willing to eat!). They also lots of sugar, white flour; typical American diet stuff.  When I go to the store, I am sticking to a budget but that "budget" cannot be at the expense of my family's health. I find that bananas, bags of apples, nuts, raisins, applesauce, and beans are always inexpensive choices, and they are good for us too!  Processed foods many of of buy cost  much more than many whole foods!  I think people who say they would buy healthy food but it costs too much are lying to themselves.   Ok, I get that if you buy all organic foods, shop at Whole Foods, gluten free, ect., YES, your grocery bill will be HUGE.  What people need to realize is you don't need to do THAT to feed your children well (and if you can afford it and that lifestyle is important to you, WONDERFUL, I am just not in that position).  This is what I overheard today shopping at Sam's Club: two overweight children (ages around 9 or 10?), "Yum! Clementines! We love these! Can we buy them?"  I don't hear the overweight  mother's response (honestly, at the moment they asked I was thinking about which produce I would be buying for my family....) but I see the family as  I approach the checkout.  In their cart is a huge pizza (Sam's Club) and a big box of crab cakes (what is the nutritional info on these? awful, fried for sure).  The Clementines were $5.48 for a 5 lb. crate (GREAT price) yet they are not in the cart.  I know I am not supposed to judge other people, and I don't know what the mother said (I hope it was, "We already have a 5lb box of clementines at home. I bought them yesterday!"  and the kids say, "Yay!") but I want to be the  kind of mother who says, "Yes!" when my kids ask for healthy foods, and if I can't afford what they picked out (sorry, not going to spend $3.99 in a bitty box of berries) I can offer them an alternative at a price that works within my budget.  I'd love to see some comments on nutritious food for our families that every wallet can afford. Thanks for reading!!