It's a fancy name for Corrugated Iron. Basically it is sheets of painted steel. It comes in various profiles, the most common of which is called Custom Orb … don't ask me why … it's the format most people would know as galvanised iron, or tin shed.
Colorbond is usually used as a roofing material, in the country people build sheds from it. But today more and more archetects are using it to create a new look building.
Colorbond is made by BlueScope Steel or whatever they are calling themselves these days, previously known as BHP. Unfortunately there is not a lot of competition in this area to drive down prices.