Ghostwriting is project-based work, so the quote depends on the target length, amount of research and interviewing, complexity of the subject, source material, revision process and schedule. Before hiring, agree who owns the final manuscript and what is included in the fee.
What increases the scope?
Heavy research, frequent interviews, specialist subject matter, long manuscripts and compressed deadlines all increase the work involved.
What should be in the agreement?
The agreement should define deliverables, milestones, revision rounds, confidentiality, payment stages and ownership of the completed text.
Start with a manuscript brief
A clear audience, purpose, approximate word count and source-material list make an initial quote more accurate.