Haha yep Steve pretty much said it already. If you can look to get vitamins from the food you eat because a) it will be cheaper and b) the vitamins are in a much more bioavailable form. Your standard vitamin supplement, while never bad to take, doesn't benefit you as much as you think. It varies greatly depending on the ingredient, but the I.U. and mgs you see on the back of the bottle could be cut by as much as 2/3 when absorption time comes around.
A renound nutrition professor of mine once said, "You are literally pissing your money away."
There are basically two types of vitamins to be concerned about here: fat soluable and water soluable. As the name implies these vitamins are found with their respective carrier. Here's a quick break down:
Fat Soluble - Milk, egg yolks, liver (huge vitamin source), wheat germ, some green leafy vegetables, squashes, carrots, butter, cheese, fish, etc. and etc. are all good sources of fat soluble vitamins. Your body has an increased capacity to store fat soluble vitamins so don't beat yourself up if you don't get every single I.U. of every vitamin every day. In fact, some are actually made by your body like Vitamin D and Vitamin K.
Water Soluble - Your body has almost no ability to store these vitamins and therefore they must be replenished every day. That is not to say you are gonna turn in a some ricket stricken, scurvied little goblin if you don't, but the effects associated with deficiency tend to show themselves more quickly. The sources are pretty similar to that of fat soluable vitamins: green leafy vegetables, nuts, liver, milk, cereal grains, meats, potatoes, and citrus fruit. Of special note is vitamin B12 which can only be gained from animal tissues and Vitamin C which comes from citrus fruits. *Fun fact* Did you know humans are one of the few species of animals that cannot make their own Vitamin C? Therefore, it is an essential nutrient in our diet.
I'm trying not to sound like some stupid guru. The point I am trying to make is simple (and one Steve mentioned additionally). You don't have to feel scared or compelled to believe that taking vitamins supplements is necessary. A balanced diet is more than adequate. The same can be said of any and all nutrients.