I posted on this two years ago but it bears repeating. Eating local is about keeping your money in your community and eating better, fresher food. Knowing the people who grow at least some of your food is nice too. It is not about the energy costs of transportation, as this NY Times op-ed notes:
It takes about a tablespoon of diesel fuel to move one pound of freight 3,000 miles by rail; that works out to about 100 calories of energy. If it goes by truck, it’s about 300 calories, still a negligible amount in the overall picture. Overall, transportation accounts for about 14 percent of the total energy consumed by the American food system.