Follow one of those large spinning cement trucks home.
They will be happy to sell you a lifetime supply for about 15 dollars.:)

Mykarma, Fiber mesh isn't necessary for planters. If you want to add an extra step send me an e-mail. I live in your area and I'll get some for you. For a small planter, 12" X 12" you would use a pinch of fiber. Billie

Look in your yellow pages under Concrete RediMix or Concrete Pumping Services. One bag will do a cubic yard of concrete (mixed), that's 3ft by 3ft x 3ft, 27 cubic feet. A pinch is right! But if the bag is likely to get wet, put it in a Ziplock -- the bag is designed to break down with moisture. One bag costs about $10.

Sue

This is where I found fibermesh, http://www.concretedepot.net/catalog/index.php
it looks like they also have colors to add to cement