Agreed, it's not always easy to get all the nutrients your body needs from food, especially if you're on a budget. I take a One-a-Day Men's Health multivitamin daily, and make a shake containing a scoop each of Gatorade and ON Instantized Whey after each workout to help muscle growth.
A good website to watch your nutritional intake is
http://www.fitday.com. I used it a lot when I first started out to track calories and make sure I was getting a pretty even balance of protein/fat/carbohydrates. Good luck!