Jim Henley at Unqualified Offerings has a conversation going about "fair market value" in eminent domain cases. He argues that
as a matter of justice the victim of a forced sale is entitled to an inconvenience premium. My house is "worth" a certain amount of money. But it's not currently worth it to the Henley family to move for that price. If it were, we'd have the house on the market right now. The victims of eminent domain, abusive or otherwise, are people who have already made a decision, by default or direction, not to sell their property. How much above "fair market value" would you have to pay me to get me to freely decide to move? At a guess, 25% would make me sit up and think about it; 50% would make it hard to say no.