To answer the question there are countless internet stores to go to where you will get your products cheaper then if you go to GNC or Vitamin World. Online pretty much makes it where anywhere in the continental US the prices will be consistent. Around the world I really do not know. I would imagine its a whole different set of circumstances given customs, whats allowed in that specific country, ect..
If you are shopping at a local store, like MM2K mentioned, you will likely get a better deal if your area has a locally owned discount store. Often the prices will be better than bigger chains but its not a guarantee. As for the bigger chains, I just wouldnt step foot into a GNC you will always pay more..yes I'm sure someone has gotten a deal here and there or they matched a price somewhere but they always have flat out been rediculously over priced.
Vitamin World used to be good but theyve had some "restructuring" and a management overhaul over the last few years and they are now nearly as expensive as GNC though not quite as bad.
Vitamin Shoppe for me is the best of the bigger chains...the ones I stop into have decent prices and the staff will not stand there and give you some rehersed line trying to sell you whatever they get commission for or whatever upper management tells them to sell if they want to be employed the following day.
Take home lesson-internet pricing seems to be best!! Word of advice..you will see some internet sites that have prices that seem way to good to be true. My advice is to call the place before you place an order. Make sure ther is a human being you can get a hold of. If they do not provide a number I personally would not order from them. A lot of these places are strictly drop ship companies..which is fine but if something were to go wrong with your order make sure there is someone you can get a hold of.
Hope this helps..