That $20 million cost to launch a Soyuz capsule includes the cost of the Soyuz (SL-04 to the US military, R-7 family to the Russians) booster. Several million dollars of that cost is undoubtedly for the capsule itself. It's hard to find out how much a Soyuz booster costs by itself. I've heard numbers ranging from $3-15 million. Since it can put over 7 metric tons (almost 16,000 pounds) into LEO, it's cost is already less than the $1,000 a pound cost that NASA is shooting for with the SEI. I've read that the Aurora booster is supposed to be able to launch somewhere around 10-12 metric tons. Pretty impressive.

Other boosters have pretty good cost per pound numbers. Like I said before, a Proton can put 20 metric tons (44,000 pounds) into LEO for a cost somewhere around $40-60 million. Our Delta, Atlas, and Titan boosters cost a lot more per pound than Russian ones but we have to pay our workers. The Shuttle is probably the most expensive booster out there but it's hard to get full cost data for any rocket.