If you are not opposed to eating some of the vitamin-loaded foods (spinach, broccoli, tomato sauces, orange juice, blue berries and other fruits, etc.) then I think your money is far better spent on real food. If you don't like or don't eat the better foods then pills can only do so much for you. There is no amount of vitamin supplements that can undo the damage that hot dogs, bacon, lunch meats, french fries, transfats and palm oil do to you.
If you must go for pills, I would recommend being conscious of some of the potential side effects and toxicity that exist with Vit A, D, E, K and beta carotene. See:
http://www.chiroweb.com/archives/11/07/06.htmlMany multi-vits have 5,000IUs of Vit A which is high enough to cause headaches in many people (especially when you add that to the A already in your diet). So in general I would limit supplementing those in favor of some of the stuff which is harder to get from diet alone: potassium, niacin, zinc, selenium, magnesium.
Interesting reading here (check page 4 for the short version of what I am talking about):
http://libdoc.who.int/publications/2004/9241546123_chap17.pdf