Avoid dairy products. Not only are they expensive, but you're body with thank you for cutting them out (substitute: spinach, black beans, navy beans and almonds for sources of calcium). I don't touch dairy and I'm not deficient in calcium so no worries.
Buy Millet (you will find it only in health food stores); Many nutritionists believe it's the one grain that can actually sustain life. Brown rice is also very nutritious and has the added benefit in being high in protein.
Stick to eggs, poultry and fish.
Try to follow the Okinawa diet. These people live past 100 on average, without any healthy issues (still jogging, riding bikes, active sex life... yes even at 100 etc.). The average citizen of Okinawa consumes at least seven servings of vegetables daily, and an equal number of grains. Two to four servings of fruit, and fish (three times weekly). Vegetables, grains, and fruits make up 72% of the diet by weight. Soy and seaweed provide another 14%. Meat, poultry, and eggs account for just 3% of the diet, fish about 11%. The Okinawa people, like the Japanese, do not eat much dairy. So there is an emphasis on dark green vegetables which are rich in calcium. Only nix the soy, since most of our soy in North America is highly processed.
Hope that was helpful.