A complex subject for sure.
I have looked for help in this area before, and here are a couple of links:
Link to NPPA Washington, DC Discussion
My Modus Operendi was to charge for my time at a specific day rate.
Add in extras such as sets, special equipment, etc.
Add in post processing times. This can be a major portion of the cost since
products must be tack sharp and the colors need to be matched.
Whatever you do, don't under price yourself on this project and think that later on you can increase your rates once you are established. The customer never seems to understand this concept.
Good luck. It sounds like this client is likely to be a major pain in the butt...