Avg. Cost to Replace Screws

Hello! Thanks for taking my question - I greatly appreciate it!
I just received a quote to have my 10 year old, classic metal rib, roof "rescrewew" as he put it. Several (exactly how many, or what percent of them, idk) of the screws are backing out and he suggested to replace them all at the same time, and made his case to support the logic of doing that. Sounds good to me.
However I was a bit shellshocked when he quoted $4500 for the job. The house is ~2300 sqft. 2 story, craftsman style with an overall a-frame style that has 2 dormers (photo attached for reference).
Is this a legitimate cost to have the screws replaced?
He said they'd use slightly larger screws with rubber washers. Didn't mention about sealing over that, or other further recommendations, etc.

(The backside of the roof is almost a mirror of the front side)

Thanks again!

No, the $4500 is a quote just to replace the screws on the roof.
I've attached an image of the quote.
We are definitely getting a second and even third quote, but the price seems very high. However, maybe it's in line with the industry averages, which is why I wanted to reach out on here.

Thanks again!