You might want to check out:
http://www.ondura.com/home.htm

I saw this stuff at Lowe's and it seemed to be some pretty good stuff.

What price are they getting for that stuff? (just curious)

I don't recall the price, but I don't remember it being particularly
expensive. I kind of liked the idea that tou could walk on the stuff unlike
the tin.

I've used Ondura (sheds can be a very helpful platform to try out
building materials) and while it has not leaked yet, one tiny roof was
enough to cure me of using it for anything else. It's basically really
heavy-duty corrugated tarpaper, painted on the outside surface. If
you're not "walking" right on top of the nailheads, it will crush. The
standard stock material is not fire-rated at all. And it flattens out in
storage, so you need to sort of "squish" it into place to get the sheets
to run correctly. An irritating material to work with.

--
Cats, Coffee, Chocolate...vices to live by