It has been very expensive of late to be a Bama fan. With a neutral site game every year to begin the season , SECCGs , BCSCGs and now Playoffs. Over the last 6-7 years, Bama fans have pretty much exhausted their 'Big Game' budgets. Whereas the Buckeyes are just starting out on their 'run'. . Wait until they have been winning big games at this level for 6 or 7 years and see if their fanbase travels as well. If this was 2009, I bet Bama would have 70% of the crowd.
This is not a problem exclusive to Bama fans. Ohio State has been shelling out for BCS games for a while now as well. Doesn't really make a difference if it was the title game or not...hotel and airfare ain't cheap.
2002- Fiesta Bowl/BCS Title Game
2003- Fiesta Bowl
2005- Fiesta Bowl
2006- Fiesta Bowl/BCS Title Game
2007- Sugar Bowl/BCS Title Game
2008- Fiesta Bowl
2009- Rose Bowl
2010- Sugar Bowl
2013- Big Ten Championship & Orange Bowl
2014- Big Ten Championship & Sugar Bowl
I do understand your point though. Bama has won 3 national titles recently whereas OSU hasn't won since 2002. The motivation in the fan base is likely increased due to that...but it's not a huge difference. I saw no fan fatigue in 05, 06, and 08 even though OSU was getting sent to the Fiesta Bowl seemingly every year.
I think the biggest difference maker in favor of OSU may be that Bama fans will be looking forward to the national championship in Dallas. OSU fans are not confident enough in this one to do any such thing.