But if you insist. Average the price per acre and times it by the amount of federal land.
But, if it were given back to the local counties, the control and taxes would go directly into the local county coffers.
The price per acre is going to vary enormously depending on where the land is and what it can be used for.
As for it belonging to the each state, that may very too depending on if the land was acquired before the state became a state. Obviously, land which was Federalized while the locale was still a territory, isn’t going to be sovereign land of the state.