The new d90 shoots movies.
What you will probably concerned with is 'noise' as you'll probably need to use high iso.
I have the d80 and wouldn't recommend it for high iso.
Can you post an example of the type of thing you'll be shooting?
It would give us an idea of what iso and shutter speeds you'll be needing.
I'm not sure how the d90 does with higher iso but it will cost above your budget especially since you'll probably need a fast lens, too.
Others more knowlegable will answer this I'm sure.