At present, it is limited to some millionaire only because the space tourism facilities like space station were not developed yet so if some one want top travel in the space. He/she must depend on the space station currently used by the various agencies.
To start space tourism, it is essential to set up the space station facilities to give accommodation in the space. It needs combine efforts of the space travel agencies to invest in the space station. It needs huge investment to setup the space station.
The first challenge is investment in the technology and second problem is budget for the space tourism. There are limited people afford to travel in the space due to both the limitations. Apart from these two problems, there are other problems like design space shuttle to travel in the space as well as setup of training centre and medical checkup facilities in different earth stations.
The opportunities for the space tourism are galore but the main problem faces by the space travel agencies in terms of technology and cost of travel in the space.
The space tourism is only making possible when the basic facilities establish and space tourism get cheaper in the coming years.