That is a great question, but it kind of takes the shine off don&#x27;t you think? :-)<p>One of the things I look at from time to time is what sort of burn rate I&#x27;d be willing to tolerate while &#x27;retired&#x27; (which is code for just doing what ever the hell I want without having to fit it into other agendas). And, because it showed up here on HN once, ran the numbers on a missile silo. The one I was looking at was less than a million dollars to purchase but my brother in law, the civil engineer, gave me a list of things that would have to be vetted&#x2F;fixed before occupancy. Since it was a vertical silo I was thinking a 10 story living arrangement built inside the silo itself, with floors going down from the circular top floor and an elevator in the middle.<p>We figured that construction, retrofits, and infrastructure would cost about 3 - 6 million (depending on how much corrosion and toxic waste cleanup was required to remediate). Power for pumps to keep it dry during the wet season, insurance, maintenance about 7K a month (it costs a lot to pump water up a 100&#x27;). We figured you&#x27;d have to start with about $10M to exit the other side with a &quot;self sustaining&quot; environment you could live and work in (but a seriously &quot;fun&quot; environment to hang out in. You could pay someone $12K a year just to come out once a week and restock the larder with consumables.<p>The school looks like a much simpler setup.