Do you have a show-reel of stuff you've already produced or worked on?
What sort of experience do you have and what level are your target clients?
What sort of post wizardry will be required?

Last thing I want to say is charge £10,000 a job, if you've never done this sort of thing before, and you're making a vid for a local student band.

The camera hire bit is the easy bit, just charge it to the client on your invoice (and maybe add a few quid for the bother).