I'm one of those people that could never afford a ride on such a trip even if it was open to the public. BUT, I sure will try to be out there getting some pictures of the event!
The trips last fall were cheap. I think the Chattanoga trips were $30 (including the $20 admission to TVRM's Railfest), and the long trip was about $65 or so. Considering NS ended up providing a free boxed lunch AND dinner (the latter of which was NOT planned for and arranged at the last minute when we ended up running very, very, very late for a variety of reasons) as well as unlimited drinks and snacks on the train, and--of course, the chartered bus return, it was incredibly good value for money.