They can't "buy back" what was never theirs!
Object to the term at every opportunity.
This confiscation, if coerced (at gunpoint or the threat thereof), is not a business transaction, but the armed robbery of a gun owner. I do not care what "compensation" is thrown at me for something I do not want to sell. It is still armed robbery conducted in violation of the Constitution under color of law.
Violation of 2nd Amendment, 4th Amendment, 5th Amendment, 14th Amendment. No process which violates the 2nd Amendment has any legitimacy, therefore, none can be called "due process of law".