Buy the land...? Why not a simple act of Congress to cede the land to a sovereign State?
The government makes a lot of money off of federal lands through mining rights, grazing rights, and the like. If they are going to lose revenue then why shouldn't they get something for it by having the state buy the land? Especially since the state will turn around and collect all the revenue going forward and not just the part of it they currently get. I'm sure we can come to a deal.