Sorry I cannot offer anything technical - but Arkady and Dazzajl are right, it comes down to confidence to ask what its worth, and this might risk losing a few jobs, but if they wont pay for a professional service, they cant have one, they'll end up with some kid and no experience doing it - if money is the clincher.
Im a strong believer in you get what you pay for - and that doesnt mean you necessarily get ripped off. This is an expensive art, cameras, lenses, flashlights - all cost a hell of alot even at consumer level, what your talking about is definitely pro level territory and if they want that they will have to pay for it.
Better to quote them big, and turn up looking like your worth it with all the gear, than trying the blue peter approach and them being cheerful about the cost but p****d about the results later.
Also the fact is if you dont rate yourself nobody else will, so take a deep breath and go for - demand what you think your skills are worth, if thats too much for them I dont think its worth you wasting your time and effort.
Not much help, but hopefully some - good luck:thumb: