Mankind has had a way of sending explorers to extreme places sometimes just to gain understanding and data, sometimes looking for new places to live. With our increasing tech base being able to take us beyond our atmosphere, it is only a matter of time before some billionaire wants to set up housekeeping on the Moon and open the first Motel on the Moon. Others like Bigelow Aerospace have been wanting to set up hotel in space, and it looks like they get their chance using the Space Station after 2020..
But putting a base on the moon, one that can become relatively self-sufficient with hydroponics and materials processing there on site with lunar regolith and basalt for base materials including oxygen. If enough water ice can be found, then at first the major imports might be high end foods and bulk nitrogen. But it would turn into first a research station and second as a tourist spot for the over-wealthy building it's way to self-sufficient quickly.
For me the problem comes in with the history of Governments using either their own military peoples, to throw into the hardships, or like the British did with the Colonies and then Australia and sent their poor and criminal classes there to flood the area with colonists. Robert A Heinlein did a good analysis of this in his Sci-fi work The Moon Is A Harsh Mistress, 1966, where the prisoner/colonists force their freedom from Earth. Some say this was a piece that actually slowed down the space program due to the whole politics of the people to be over our heads with weapons like mere rocks launched from mass drivers. A well directed chunk of rock 20ft in diameter, with a thin iron skin to hold it together, basic attitude and deorbit control and high angle direct impact with multi-tons of rock at several hundred miles per second can make one heck of a hole, with no 'explosives' involved. Was a scary thought during the Cold War and still merits consideration.
However, that aside, with the ISS EVERYTHING aside from solar power comes up from the planet. On the moon there would be space and materials to be able to make things, if you take along the right equipment to be able to Build with, and bootstrap up, then the Lunar base can be rather self-sustaining, growing their own food underground (like we are having to in some cities even now), be able to mine for ice to use for drinking, agriculture and splitting into hydrogen and oxygen for both fuel and breathing (again, need the nitrogen, some can be liberated from rock, but more oxygen is locked in rock than nitrogen normally so it may need imported). Recycling will be a Must, and there will be very little that will be made as 'disposeable' there for some time, but perhaps that would be a boon for us here as well, getting away from a Disposeable Everything Society and the pollution challenges it brings would get a boost from such a program where everything HAS to be reused or recycled.
But in time I expect that mankind will find the Moon to be no more of a far off, extravagant vacation spot as Hawaii was in the 19th and 20th Centuries, to the point where it is a normal enough destination and not particularly special or difficult to get to anymore.
And, even today, you can have a robot wander around Hawaii for you and take pictures, but would you not rather BE there Yourself and take those pictures, to see for yourself what is over the hill? The robot is not into laying on the beaches nor in cold tropical drinks. Human Nature seems to include the type of people who, like myself, want to GO and to DO, leaving the comfortable folks back in their comfort and finding the places that while they may be hard to get to, brings an intangible reward of Having Been There, Done That and finding things that are of interest to those who stayed in their comfort.
But when it comes to comparing the ISS to a Moon Base, the lunar base wins hands down as it is the nucleus for a self-sustaining system. The ISS will always be dependent on outside resources, even if it does end up growing a portion of it's food (and atmosphere). But the moon the materials there are usable even as a shield against radiation in the first place: put up a rigid structure and cover with a few feet of regolith as meteor and radiation shielding. Much activity is going to be below ground and much of the material is going to have to be fabricated in situ, but there should be plenty of metals to refine and it may well be that in the future it is cheaper to build spacecraft there and launch from the moon to build very large ships or structures in Lunar Orbit, much cheaper than trying to do it from Earth, with the high cost of launch from here which is always going to be a limiting factor due to the difference in gravity.
So there is no real comparison as to the cost, even. Mankind WILL Go There and Do That, once they get the idea into their head and build out the tech needed. That is how we have people in Antarctica even, or in deep sea subs, checking out the deep trenches etc. We have gold miners working some 7 miles down into the crust in South Africa, so we are a form of extremophile ourselves in that we are able to build environmental controls to take us to these places we could not otherwise go. So expect us to put men in the moon, to put up even better space stations, like the one they want to orbit Luna as a Gateway to the outer planets.
The Money is already being spent, and a lot of it is Corporate Money, not tax funded, and so we are going to see things accelerate now that some people are seeing real profit in it. Being able to reuse rocket stages is a big thing and the engine tech that SpaceX is going for is going to be a major game changer with the use of liquid methane. In some ways Musk is right about getting to Mars, as there is an atmosphere that can be recombined to form the methane fuel as well as oxygen and so the ability to set up a refueling plant there in the first few launches. The first couple/few craft may have to expect to be there for some time while the structures are built and systems going, experiments undertaken etc before they manage to produce their first fuel runs to get enough fuel to be able to set up return trips. But that is all in the planning stages presently, but Luna, as a closer gateway and jump off point is a logical and practical idea.
