It's funny I have a job on at the moment which is shooting doctors administering BOTOX to women, and I am getting bloody great money for it, it's ongoing too which is fantastic.
Underwater stuff which has harder, weather dependent, involves a shitload of gear is so much harder to get consistent well paid work.
I think the industry that you are pitching too makes a huge difference.
Big corporation have no issues with dealing in big numbers... in fact I reckon if you are too cheap it puts them off.
Small dive companies which are struggling to keep there head above water in winter, if you say 5K they say NO WAY! (hey that rhymes a little maybe I should add poetry to my skill set)
Big dive companies see the value and spend the dollars and end up with a professional job and do even better..
Sorry I am rambling, what I am trying to say is that I always tailor a quote to the company, do a little research, get a decent brief from the client and in your quote break it down so that they see why it costs so much.
Jon