You used to be able to do this in the long-ago; you'd even see people selling tickets in the classified section of the newspaper (kids, ask your parents). The

You used to be able to do this in the long-ago; you'd even see people selling tickets in the classified section of the newspaper (kids, ask your parents). The problem is, the airlines would rather make more money by selling the new person the ticket at an inflated price (presumably if they cared enough to save money, they'd have bought in advance), and from you as well in ticket change fees. This was sold to us as a post-9/11 fix to ensure terrorists didn't buy tickets, but I doubt that was the underlying reason.