Space.com has good background on Excalibur Almaz, one of the companies working towards private space flight including excursions to the moon, in their article Space Tourist Trip to the Moon May Fly on Recycled Spaceships.
Excalibur Almaz will start with refurbished Russian spacecraft:
It bought four 1970s-era Soviet Almaz program three-crew capsules and two Russian Salyut-class 63,800-pound (29,000 kilograms) space station pressure vessels.
The plan is to lift an Almaz reusable return vehicle and a Salyut space station into Earth orbit separately. Then match them together with a propulsion unit and the combined stack heads to the moon.
Wikipedia has background on the Salyut space station. The last space station, Salyut 7, was in orbit 2,216 days, was occupied 816 days, and received 12 manned spacecraft and 15 unmanned spacecraft. Quite impressive. Seems like that would be a very good platform for a trip to the moon.
Excalibur Almaz has a conservative estimate that they can sell 29 seats in the next 10 years at a range of $100 million to $150 million per ticket.
Some of the technical challenges they have are buying the capacity to lift equipment into space, develop a new propulsion system to get to the moon, build the flight control computers and life support, implement an emergency escape system, and design protection from radiation storms.
On one hand that looks like an incredible amount of cutting edge work still to do. On the other hand from my simple knowledge of space stuff, they would not have to break much new ground, merely adapt current technology and push the boundaries.
The amazing thing? For my simpleton background it looks like it’s doable. Now. Today.
Since I’m an accountant, I have to look at the funding side.
I’m assuming there would be 2 paying passengers on the 3 passenger Almaz RRV. Assuming they sold 20 tickets in the next 10 years the passengers would generate between $2 billion and $3 billion revenue. If that was their only revenue stream, which it won’t be, seems it would be enough to work with to make a go of it. (On the high side, 29 tickets at $150M each would be $4.3B.)
There is not quite enough cost data in the article to make any wild guesses on what it will cost them. But it sure does look they have done some hard work on the forecasts.
They expect they would be able to provide other services, such as private research, transport for mining near Earth asteroids, supply trips to the moon, deep space testing, putting a satellite in orbit beyond the moon’s orbit (Lagrange point 2 orbit – cool idea, check out the link).