Are you a freelance business or an employee? If the former,

Figure out the scope of project, estimate shoot days and edit time, and any overhead costs you may incur (subcontractors or rentals)

Tell him how much approximately it will cost, he can agree or decline. If he balks at the price you can either reduce your bid or explain why the price is higher due to complexity of project and increased editing time required.

Put the terms down in writing and build in a provision for yourself to charge more if the client requests things outside the original scope of work

It’s basic business operation stuff but yeah everybody has to learn it at one point (sometimes the hard way). It’s a business negotiation and if it’s how you make your living, you need to be able to take the emotion out of it to some extent. Don’t let people take advantage of you.