The thoughtful farmers at the Waltham Fields Community Farm only bristled slightly when I asked whether they plant a more diverse set of crops than a commercial farm would. They are a commerical farm. They know, to the nearest thousand dollars, the per acre value of their produce, based on a sophisticated computation from local retail and wholesale prices. They are proud to promise their Community Supported Agriculture share holders, including my family, a reasonably good deal based on dollars and sense rather than mere pounds of gross weight. Still, they know that their own sustainable agriculture principles are part of the essence of their product. They follow organic practices, but are not certified by USDA as organic, and might or might not seek such certification even if they didn't face technical hurdles, such as a challenge in maintaining the proper chemical-free buffer zone from neighboring properties in the surrounding suburban landscape. They feel the certification is less necessary when customers can meet the farmers themselves and ask any questions they like. At today's third-Sunday-of-the-month outdoor question and answer session, the farmers did have to acknowledge that the joy of knowing where one's food comes from, and how, and even helping to grow it, is a significant share-holder motivation. Indeed, sitting at a picnic table, laden with organic treats, in conversation with this sweaty dirty-fingernailed bunch of entrepreneur / idealists, with kids rolling around in the grass nearby, as the shadows lengthened in the peak of summer's sun, one has to ask: who could put a price on this?