Interesting article from Tom Philpott at Grist on the connections between cheap food and cheap labor, and the need for the sustainable food movement to address issues of class. Key paragraph:
In short, an economy hinged on cheap labor needs cheap food. And that’s the structural problem faced by Slow Food and other would-be reformers of the food system. The challenge of food reformers isn’t just to reform the food system; it’s to reshape the entire economy—to create new economic models that revalue labor along with food, so that people can afford the revalued food.
The increased availability of cheap consumer goods has long been the justification offered by apologists for free trade, corporate globalization, and the rest of the bi-partisan economic agenda. But if, as Philpott argues, “cheap” food is not sustainable, then we need to re-think the entire premise of a cheap-goods/cheap-labor economy.
A Thinking Reed 
Yeah, there might be something uncool about limousine liberals buying whatever is the most “green” food available, regardless of cost. It creates markets for unaffordable if sustainable agriculture.
In years past I used to try to spend some time buying food from inner-city grocery stores as a charitable and political act. Maybe I should revisit that kind of charity.