Hard to say. They have to cover development costs as well as flight costs. Oh, and insurance if they can get any.
Passengers will have several minutes of weightlessness during the spaceflight, and then have about 40 seconds to return to their seats, Whitehorn said, adding that the floor of SpaceShipTwo is also designed to be used during landing of spaceflyers fail to reach their spots in time.
http://www.space.com/news/060828_spaceshiptwo_next.html