The cheapest advertised price to launch people to LEO is a bit over $26 million/seat on a Falcon 9/Dragon which includes a stay at a Bigelow space station [Bigelow 2015], also in development. Current estimates are that space colonists would need about 17 tons per person for their share of space station habitat. The cheapest advertised price today for delivering mass to orbit is the Falcon Heavy, in development, at $90 million for 53 tons to LEO [SpaceX 2015], or $1.7 million per ton. For 17 tons that is about $29 million. Combining these two costs gives us (rounding up) $60 million per person. This does not include materials, construction or resupply costs. It would be assumed that government or space tourism businesses will conduct most of the research and development cost other than actually building a settlement.
Elon Musk is trying to make hundreds of flights per year economic by launching and maintaining a network of 4000-20,000 internet satellites.
There were 92 space launches worldwide in 2014.
Supporting a global network of 20,000 or more internet satellites (with 10-30 in each launch) would end up being a few hundred flights per year to space on a sustained maintenance basis and one to two thousand during the main deployment phase.
Full reusability of all stages could be technically proven in two years and a standard part of Spacex launches within five years.
By 2022, the buildout of the internet satellite network should be in full swing and the cost to low earth orbit per person could drop to $200,000 to $400,000 based upon the following chart of costs and launch frequency.
Tourism was a $2.3 trillion/year industry in 2014.
There is high cost tourism now.
$35,000 to 65000 or more for up to 1000 people per year to try to climb Everest. There is also a 0.57% death rate.
There is a Silver Seas world cruise for $1.2 million. Rich people go on a super luxury cruise with special guides.
It seems by 2025 or so there could be the market and pricing for 1000 people per year to go to space.
After that it will take sustainably high volumes of space tourists to drive up volumes and drive down costs.