You could build a rubbermaid Deep water culture (bubblers) for less money. and it's a really simple device (i.e. hard to fuck up). I'm about to build one for my first hydro grow. The guy at my hydro shop says he loves bubblers

http://www.bcseeds.com/hydroponics.htm

This is how you make individual bubblers in buckets. you can make larger ones to hold more plants in rubbermaid tubs.