$100,000.00 in 1865 is equal to $1,478,690.56 in 2012.
The 2013 figures are not yet available on this site.
Rick
According to this it would nowadays be $201,48 for $8 in 1861 but $147,08 for the same in 1863. Roger, I'm sorry, your first guess came closer to the truth, I misconceived there wouldn't have been such a remarkable inflation rate (how silly of me with regard to the wartime). Well, to get myself out of it I'd say that Gene's answer was the most true one - the hat would be beyond price anyway. By the way, does it still exist somewere?