My wife and I have been taking DualTab by Twinlab for at least six years. Have only had 1-2 colds since then. It has everything including minerals and buffer to aid absorption. I got started on them after trying to figure out the best assortment of individual vitamins along with good quality. A nutritionist said to take the Dualtabs because they had it all and were high quality. Plus, most of their ingredients are time-release, which also aids absorption.
Many on-line sites have great rates. I purchase from
http://www.vitacost.com/ as they have the best prices I've run across.