From Next Big Future:
Researchers in Sweden have created a new rocket fuel molecule called Trinitramid that could increase payload capacities 4-8 times and be totally earth friendly.
What this enables is a Single Stage to Orbit Fully Reusable Launch Vehical. The follow factors each reduce launch cost to orbit:
1) The power of Trinitramid (4-8 times cheaper)
2) Single Stage Fully Reusable Launch Vehicle (50-100 times at least)
Multiply these two factors together and you get a reduction between 200 and 800 times cheaper than current launch costs. That comes out somewhere between $2500 to 10,000 per person for access to space. When space travel becomes that cheap, a LOT more people and enterprises can afford to go, which means a lot more demand and a lot more launches, which brings in a third cost reducing factor:
3) Economies of Scale
Since fuel prices for Liquid Oxygen and Hydrogen are cheap (less than a $1/pound), then the only costs remaining are operational and upkeep costs. What this means are prices not much higher than intercontinental airline flights.
The bad news is trinitramid may not be stable enough to be used as a fuel. Even in that event, and taking out the factor of 4-8x, prices to space would still be under $5000 after a commercial space industry matures. This means anyone who is motivated enough could go to space.