However, don't despair. Far more people will go to space as visitors. So for anyone, the main, first thing you can do to get to go to space is to save. Estimates of how low the price of a return flight to low Earth orbit will get vary. The target of the Space Tourism Study Program of the Japanese Rocket Society is to bring the price down to about 1 million yen (about L7,000 or US$10,000), on a turnover of about 1 million passengers per year. However, the demand is expected to be so strong that in the early stages prices will be considerably higher - perhaps 5 million yen ($50,000). As the number of vehicles grows, the number of flights will increase, and prices will fall to 2 million yen over 5-10 years, and then to Y1 million if possible.
Many people in the "space industry" find the idea of 1 million people per year going to space almost inconceivable. Yet people in aviation find such a figure almost inconceivably small - less than 1/1000 of the 1 billion passengers carried on scheduled flights each year - that is, just 8 hours of scheduled flights around the world! So it's clearly not an unrealistic target!
So if you want to have $10,000-20,000 (Y1-2 million) in 10 - 20 years, you need to save $1,000 (Y100,000) a year, give or take. Better would be to save $100/month (Y10,000/month). That way, the longer it takes companies to get services up and running, the more money you'll have ready to pay! But remember, that's got to be separate from your other savings - because you are going to use it!
In order to stay longer in space, you can work in one of the businesses that will set up in orbit. There will of course be opportunities in manufacturing - aerospace vehicle makers, spaceline operators, orbital construction, electric power, extra-terrestrial mining, chemical engineering and other fields. So you can study, and make the right career moves to be well-placed for these.
But for the foreseeable future the hotel business will probably employ as many people in space as all these other industries put together. Note, just like hotels on Earth, the day-to-day work won't be particularly well-paid. But it will be in space, which will have its own rewards!