Scoping/quoting ballpark

Hello documentarians!

I’m an experienced videographer, with lots of solo experience for weddings, low budget “commercials” (below $5,000), talking head interviews, etc.

I got an inquiry through a colleague for a “Ken Burns-style documentary short” about a guy rebuilding a unique historic home that burned down two years ago. Homeowner is the client, and “money is no object” for the build itself, but he won’t commit to a number for the documentation aspect, and basically said “industry standard costs” in his email exchanges.

I’ve spoken with two production companies I work with periodically, and I got $20-25,000 from one and $200-250,000 from the other.

So what does it actually cost to do a Ken Burns doc per hour?

Specs: 45 minutes to an hour total length

It’s expected to take 18 months to complete the build, with monthly visits to the site.

Talking head and stationary camera interspersed with photos and voiceover. Aerial b-roll.

Professional narration.

Thoughts or resources would be greatly appreciated!