How does cost per seat-mile differ between commercial and private jets?
I did some basic math to figure it out in terms of current gas prices.  I got that a private jet is about 6x more expensive.  Keep in mind it is probably more in reality because these jets aren't being used as much as an airliner so the rental price will be higher as well as the fuel.  But like I said, this was just an estimate based on current fuel prices and performance of an airliner vs a private jet, to give you an idea of the cost difference.