The three main stages of production are:
Pre-production: Planning, scripting & storyboarding, etc.
Production: The actual shooting/recording.
Post-production: Everything between production and creating the final master copy.
Pre-production: Arrangements and preparations are made for the shoot, such as hiring cast and film crew, selecting locations and constructing sets.
Post-production is a huge portion of the production process as it is when editing, title credit creation, audio mixing, and color correction occur in a music video, promo, tv show, movie or commercial.
Production: The actual shooting and recording of the project.
Cost is calculated by:
All stages of production
The many hours it takes to edit and complete your special project
Taking into consideration each of those phases and the time and effort put into your project will give you a better understanding of the prices that are offered to you.