Just to add, you can find document to advice heritage group about cost of 3D scanning.
It depends where you are, but if it is UK you can check document from HE or loterryfund (I reed it a year ago so I am not sure I can find quickly the link!). Then you can support your price by common practice.
I think basic photogrammetry was around 500 a day, laserscan or more advance photogrammetry can reach 1-2k.
Even using a drone for a day for 3D model would result in a ~1k fees.
Even a photographer for a day can cost 700 pound, even though it needs editing after, with a 3D models you might need even more time (both machine and people)
PS: I am not a freelancer, I just collect info about that