Keith's note: I have no idea if this is even remotely accurate in whole or in part (seriously doubt it). But it sure is funny. Anyone who has different math, please feel free to post. According to a post on Reddit:
"The fuel costs are, according to Musk, about $400.000. Let's round that off and say 500.000, so that the empty rocket costs 56 million.
The Falcon 9 carries about 475 tonnes of propellant. If we can convert dollar bills into kerosene and oxygen perfectly, using 1 dollar bills and assuming a mass of one gram, we get a fuel cost of 475 million dollars. So, now a Falcon 9 costs 531 million dollars, and lifts 13150 kg. That's 40380 dollars/kg. The space shuttle cost 1.5 billion dollars per flight including everything, and could get 25 tonnes into LEO, so that's 60.000 dollars/kg.
Holy crap, you're right. (don't take this too serious.)
Edit: If we can convert dollar bills into kerosene and oxygen perfectly. Stop telling me that paper doesn't burn hot enough."