Food: $200 (If you cook and eat very rarely out). However, the average cost of a "cheap" meal is roughly around $10, so do the math for how much that would cost per month.
Transportation: If you are going to live in the valley, you will need to get a car. Things are spread far apart and I am not even sure how good public transport is. If you wanted to come to the city (SF), every now and then, that would be roughly $14.00 by Caltrain for a day pass.