Here is the plan. I am going to use a 2 by 4 frame and plywood "floors". Its not the most efficiant spacewise but its cheep and I have most of it. In fact it looks like 1/4 lag screws are the only thing I need, but I will probably pick up a few extras for stock.

Qty. Description

2 12x96x.5 inch plywood

Aprox 100. 3-1/8 "deck" screws

6 3x1/4 lag screws

7 8 foot 2 by 4s