I've often considered what he mentions about people buying up the land and basically turning it into a "freehold". It's, as an example, one of the only ways I think something like the so-called "Venus Project" could ever work... They buy up a large island somehow and use it for their operations.
But I think the main issue with these sorts of projects is that if you want anything more lofty than comfortable, self-sustaining communities*; you need to exist in a world that functions similarly to your own community. I.e. a world where there isn't private property or government run land, where everything that isn't personal property or the property of something like a worker-owned cooperative is basically part of the "commons".
I say that simply because if you want to indulge in some lofty activities like forming an organization dedicated to space exploration (a worker-owned and run one) then you're going to hit a wall when you need a lot of the resources to build your rockets and equipment while the outside world is basically as it is now and won't give you those resources unless you, an essentially communist/moneyless society, can pay up for those resources.
Something like the Venus project's ideas would probably hit a wall in that it will likely become apparent that any given island or small territory's resources can't be used to fully build things like this:
The initial costs of setting this sort of community wouldn't be all that cheap at all but it could eventually become quite long-lasting and self-sustaining, only, in my humble opinion, requiring small amounts of money to maintain their desalination machines and buy parts for the electrical systems of their houses, and also pay for internet connections from the outside world if they're interested. For that I guess they could up their food production in their gardens and create a surplus they can make small amounts of money from annually in order to pay for those sorts of things that they would likely only need to pay for once every several years if the initial equipment is well-made and well-set-up.
But of course, I've only thought of how the society would sustain itself in terms of its overall needs so that the locals can live comfortable lives without needing to work much annually, much like various historical farmer communities. The real challenge would prove to be how such a society would be run. But luckily, we have the detailed works of generations of anarchist, communist and socialist thinkers, some who've put their ideas to the test.