I was thinking about this today. I idly added up how much it would cost to rebuild my main bike from scratch. Pretty mind boggling the figure you come up with after a while. And I don't imagine trying to convince an insurance loss adjuster that something like a headset can really be worth well over £100 would be easy.
I know the feeling. I guess I was very fortunate that I worked for a big bike shop when I built mine, although I suspect I gave them back in sales more than they gave me in salary that summer!!