If you're looking for a high def motion camera that's considerably cheap, you could try the Speed HD7Z. It does up to 720p, which should work pretty well for your edit. They're on ebay and other sites for around $200-500. I'm not sure why they are so cheap, while having high def capability (I'm sure if I knew my digital camcorders better, I could spot something in the specs that points to the reason--maybe it's the fact it's a completely off-brand name camera). Anyway, after some more research, I might pick it up myself, so if you still need some cloud city background elements in mid to late september, I can get together some shots for you.

http://www.speed.com.hk/product_details.asp?id=23184&groupid=3