In the late 1400's and 1500's only governments could finance ocean voyages to the New World and to Asia from Europe.
By the early to mid 1600's larger private fortunes could finance such ventures because the technology to build the ships nessesary and the medical technology to prevent things like scurvy made it more affordable.
By the 1800's just about any company could own a ocean going vessel and even poorer folks could buy passage across the ocean to get to better lands, so to speak.
Starting in the 1900's individuals could and did start with ships that could sail around the world.
As the technology improved, costs came down and IMO, the influance of private business made it happen even faster than if it had stayed in the hands of governments only.
I belive that the same will happen with space technology. Admittedly, there are MANY greater hurtles to overcome, but technology is advancing faster each year.
I, personally, am routing for the private space service to begin with full force. I highly doubt anyone would actually put an ad on the moon you could see from earth, but I do expect places that are already planning on becoming Space Ports to thrive a great deal in the next 50-100 years. Oklahoma has some impressive plans to turn an old Air Force base into a space port. And the Mojave Airport has actually put in an application to the US Government to be clasified as a Space Port. The reason being that the top contender for the X Prize is using the Mojave Airport to test it's entry craft the SpaceShipOne. While it hasn't achived orbit yet, they have set a new record for the highest non-governmental manned flight.
Check out X Prize
The key differance between space travel and ocean travel is that there were obvious financial benifits to traveling to the New World and Asia. Trade, gold, land, exotic plants/animals, etc. Without some sort of financial reason to go to space, all this could be moot.