Okay, that may not be how we do it. But still, it's something fun to consider, and there's some real math put into this graphic for "Mission: Space House," as they call it. They picked out a viable rocket (the Falcon Heavy) and figured out an approximate weight-to-square-foot ratio (200 pounds per square foot for a single level). At the end, you can see a brief history of spaceflight costs and how they stack up to the estimated price of you shuttling your pad to space.