Now that we know Clemson will play Alabama for the national championship, I rechecked ticket prices on one of the nation's largest listing sites, TicketCity.com.
Oddly enough, tickets were more expensive back on December 19 than as of this morning. You were looking at $621 and up nearly 2 weeks ago. This morning, Alabama upper deck tickets were available from $487, and Clemson from $559. I would expect those prices to rise rapidly as the number of available tickets dwindle. Follow the link below to be taken directly to the ticket inventory page.
CFP National Championship - Alabama vs. Clemson - as low as $413 (as of 3:43 A.M. Eastern Time on 1/4/16).