Honestly, I hate the "supplements" world we live in. It seems like everyday someone comes on this forum thinks they *must* take supplements in order to even be considered "healthy." Don't waste your money on expensive supplements. Most of them are either bogus or not really needed. Supplements are just that - supplements to your food source. Not really needed, but for certain people, it is.
Taking multi will not hurt you in any way. It's really a hit or miss when you buy one. If you are already getting enough micro nutrition from food source, then taking multi will just be a waste of time. Store brands are better, if not equal, to name brands. I agree GNC is a waste of money, but other stores, such as your local NEX, Walgreens, etc have store brands that are just as good. Just read the labels and ingredients along side one of the commercial brands and most of the time they're the same thing.
To be honest, I recommend *not* taking multi unless you are cutting or on a specific diet ordered by a diet. Cutting, or "losing weight," means you are not eating enough food so it wouldn't hurt to take a multi to ensure you are getting your daily supply.