I have to vote for the starter set idea. Something akin to the "Lionel Scout" or the M&St. L sets currently being offered in O. Maybe reissuing one of the classic Flyer sets, like one of the sets with the Reading Atlantic or something.
While American Models or someone else may have sets available, they still aren't completely in range of someone who could afford only one of the starter O sets, and if you would want more interest in S gauge, a basic and affordable starter set would really help.
Although Lionel has done more with Flyer as time has gone on, I still think they haven't done what can be done to make the brand name better known.
