Whatever they offer is typically negotiable to a point
and they pretty
much expect you to challenge their valuation. The burden is then on you
to prove your figures.
I don't really think this is true. They accept your premium based on what
you tell them the value is. If they want to dispute that, they should do
it prior to accepting your premium.
Now, unless someone is trying to defraud the insurance companies, lawyer's
expenses will be part of any judgement. I doubt very seriously that
insurance companies want to take these things to court, expecially on
ones they can't prevail on.
BTW, I had an insurance claim filed on an IMSAI that I shipped to Italy
(FedEx). FedEx called me and asked how much it was worth. I told them
and they paid the claim.