In this listing, the cheapest price for a used 737 is $750K. I have no idea if these prices are for planes in flyable condition, but the odds are some maintenance work would be necessary, which should bring the fly away price well over $1m. Compared to that, two plane tickets are peanuts. I've left out the flight training as an incremental expense, because they need that regardless of how they acquire the plane.
True. But all the speculation is that the plane would carry a nuke. If someone has the wherewithal to acquire a nuke, they can also get a plane to deliver it.