"The figures cited above are inaccurate and misleading, however. The $42 million cited for Bush, while roughly accurate, doesn't include the cost of security and other incidentals covered by federal and state governments. The $120 million cited for Obama (which is actually a bit on the low side) does include those costs. It's a false comparison.
Traditionally, everything except security, clean-up, and the swearing-in ceremony itself is paid for via private donations. By most estimates, the Bush inaugural committee raised and spent about $42.3 million. At last report, the Obama inaugural committee had raised and spent almost exactly the same amount ("more than $41 million," according to the Associated Press).
Factoring in the rest of the expenditures, in 2005 federal and local governments were tapped for an additional $115 million to cover security, swearing-in, clean-up, and a paid holiday for federal workers on the day of the Bush inauguration. That adds up to a combined total of $157.8 million from both private and government sources."