I picked up a white housing off this ebay seller:

http://myworld.ebay.com/freetrade21

I bought it to replace the damaged black housing on my n9, after a couple of bad falls onto the road.

The replacement was quite tricky, i stripped a few of the screws trying to remove them, and ended up having to drill them out.

Unfortunately I managed to damage it somehow, though i'm not exactly sure where. The phone boots up ok, but the camera no longer works. It just says "camera not responding".

So, it's doable but not without risks