Is it possible the vitamins are all made in the same production facility? I've heard brand name prescription drugs and their equivalent generics are often made in the same facility, but generics cost less because there are no marketing dollars spent on them.
The reason I ask is that I had been using GNC's Mega Men pills, but I decided to switch to The Vitamin Shoppe's Ultimate Man pills becaue I hate GNC. The two brands of multivitamins have the same color, size, shape, and smell, and the ingredients are pretty much spot on. Of course, The Vitamin Shoppe is about 40% cheaper.