How much building debris is salvaged after a natural disaster?

When I see the beautiful iron work, stain glass windows, door hardware, and tiles that are left in the rubble after tsunamis and earthquakes I've always wondered how much material is salvaged and how much is thrown away. I would love to buy wrought iron work salvaged from a building that was destroyed in Katrina as a way to put money back into the local economy in New Orleans. Is there a non-profit that does this type of work?