Cost of food while camping ... does it have to be high?

We just started fulltiming and have been on the road for two months. A couple of things I have figured out: A lot of food (at least what I eat) is regional - you just can't buy the same stuff all across the country. It costs us significantly more now because we have to buy in smaller quantities and we can't always buy on sale. I really miss my local grocery store - great prices and selection. The worst store I have found so far was in Louisiana - the prices were shocking to me, even though it was a large chain.