There's a big stink now about this. Municipalities are taking homes to make homes. That is conceivably a valid government act, if there's something very very wrong with the home taken. If that's true, twice market should be no problem as the seizure price.
There's a 2:1 rule called Vacarro's Rule in computer programming too. If it isn't a 2:1 improvement, it's not worth programming. It's a valuable rule, even if it is just now getting out beyond me and Vacarro.