Various people have tried to found new countries, mostly meeting with failure. An obvious question is: what did they do wrong and what should be done differently? I am far from an expert on the topic of nation-founding, but I have some strong opinions on the subject anyway :).
One of the problems with government today is that it is too big. It attempts to use heirarchic structures and central planning to deal with vast numbers of people, which just doesn't work that well. Many planned nation projects, despite being libertarian, seem to suffer from similar difficulties. People have a glorious vision, and rather than trying to figure out what the small steps are to get there, they try to do it all at once. This is natural but disastrous. As case studies, consider the three "city at sea" projects: The Freedom Ship, Residensea, and World City. It is unclear whether The Freedom Ship was a scam from the beginning, but if not its size (and nine billion dollar cost) make it extremely unlikely to succeed. Here is some evidence that it is nonviable.. WorldCity was another project that never got off the ground, because it couldn't get the billion-dollar loan it needed from Marad. The only ship which is actually being built is ResidenSea, which was the smallest.
In general, the larger a project, the more organization it takes and the harder it will be to get started. Anything that can be done by a few people is much more likely to happen. This is not to say that nothing can ever be large and complicated - the world certainly contradicts that - only that big things generally start small and grow. Consider Burning Man. It started with a few people, and is now an event that draws 25,000. The world is full of similar examples. Big companies usually don't start that way. Life began as unicellular. Organic methods are much more likely to succeed. And a nation, if small enough, could be started by a few dedicated people. SeaLand is a great example.
A related principle is minimal reliance on outside investors - instead using word of mouth and the founder's funds. Rather than begging, fast-talking or borrowing money, why not just do what you can afford when you can afford it? The investors and the early builders/founders can be one and the same, which seems much more realistic than trying to find "angels". If this means that you have to start small, fine. If a small, island nation is succesful, it will have gained the momentum to expand.
Decentralization should be key. Rather than trying to centrally plan the infrastructure, start out by making sure the basic necessities of life are present and let the citizens take it from there. The organizers of Burning Man don't try to truck food & water for everyone to the desert. They supply toilets and some medical resources and let people handle the rest themselves. Finding, buying, and beginning to develop a piece of land that can be free from governmental interference is a big enough task already. There is no need to micromanage nascent ventures.
This realistic take on the vision makes founding a country less of a pipe dream. There are a lot of islands cheaper than a house in Silicon Valley. A big island is more, the right location may be difficult, and infrastructure is expensive - but if the founders don't have the money, they can start small and bootstrap. Go down for a couple weeks every few months and make the place a little more civilized each time. Start out as a hobby & a vacation and turn into a permanent home. Let interest grow steadily. Given that people have signed on to scams, it seems reasonable to expect to be able to raise some interest in the real thing, even if a small island with limited infrastructure is a lot less romantic than a brobningnagian boat-city.
For information on lots of nation founding attempts (mostly failed), see the Footnotes To History webpage.