Hi,
Supposedly, eminent domain is for "fair market value." If you do not get a fair price, you can make a counter offer and even take it to court. But it is your duty to prove that the offer is below fair market value.
As far as being required to sell. One person here in GA was able to sue the City of Sandy Springs successfully. They needed to widden a road and tried eminent doman. However they also wanted to make a linear park.
The defendent proved in court that the eminent domain for the road was properly used (the defendent did not contest this). However the use of eminent domain for taking more property for the Linear park was improper use.
The idea that the eminent domain can be used to "steal" someone's property is an urban myth BUT as with so much today, we are not taught it in school and so many are ignorant of how to fight it.
Lawyers are trained to know this type of stuff but if you do not know enough and do not have the cash to fight it, you can not make an informed decision. Catch 22.
Doug vV