By my best assumption the ins. companies use a model similar to the KBB value taking into account miles drive and other factors. Thus yielding the low ball number.
If this were my case, I would find comparable vehicles in similar condition and miles and base the sale price (market value) of those vehicles. I would stay away from using eBay as any sort of authority for pricing anything.
Get a copy of the police report which should have an estimated dollar value in damage which the officer / public safety assitant who wrote the report documented. Their number also not an authority but hopefully that number is above the insurance companies.
Finally I know others have used JohnB and even Chuck Tator as authority experts. Im sure those guys would have no problem assiting with a faxed/mailed document.
The replacement value and actual value are two completely different entities in the insurance world. They want to give you the actual value and you should fight tooth and nail for the replacement value which is just that. The $ amount it will cost you to replace your vehicle to the condition it was in right before the crash. Obviously totaled, that would mean the $ amount it will cost you to replace your vehicle with another one.
If your vehicle is not totaled the diminished value is the difference your car will be worth after the repairs to the value it was before the damage. Ex your car is worth 50k. Damages to fix cost 10k. After repairs your car now is only worth 35k. The difference is an additional 5k the insurance "should" be responsible for.
Hope that helps.
