it's hard to get a handle on how much a manned Soyuz mission costs. The Russians keep that kind of information rather close to the vest. I've read several reports that suggest the whole mission only costs them about $20 million. When you consider that they have almost no R&D costs to amortize (the Soyuz capsule and rocket have not changed very much over the past 30 years) along with the fact they don't pay their employees much (or at all in some cases), that $20 million figure could well be realistic. If it is, then a single tourist is actually paying the full cost of the flight that the Russians are obligated to fly to replace the ISS lifeboat every 6 monts.

It wouldn't be very difficult to develop an enlarged Soyuz capsule along the order of the Fat Gemini proposal. The Encyclopedia Astronautica website appears to be down for the moment (hopefully) so I can't provide a link to Fat Gemini. They'd planned to put a second tier behind the main crew seats on a Gemini capsule that could've carried several astronauts (5-7 if memory serves) on a Titan 3 booster. With their upgraded Aurora booster and a larger crew compartment, a Soyuz-T (tourist) flight could possibly carry as many as 5-10 tourists for a mission cost little higher than their current Soyuz missions. In other words, they could use that capsule to carry passengers for perhaps $2-5 million each and even make a profit. That same vehicle could replace the CRV as well. From what I've read, the Aurora is a reengined Soyuz booster capable of orbiting 11 metric tons, more than enough for the tourist mission.