1864
Indian cents rotated between 90 and 180 degrees are estimated to be at the R4 level according to
http://www.rotateddies.com. That is, there are estimated to be up to 200 surviving specimens. If you search for rotated
Indian cents on
ebay, you will *always* find several 1864's, usually the 1864-L, and usually an 1897 (which the same seller always lists for way too much $$). Anyhow, 1864 are some of the more common ones. I have an 1864-L rotated 175 degrees, an 1864 no L (bronze) rotated 105 degrees, and an 1864 copper-nickel rotated 95 degrees. Although supply may be low, demand is also low as few people specialize in them.
As far as value, most of the copper nickel
Indian cents in G condition go for $25. Except for the 1859, which is fairly rare to find rotated and might go for $50. The 1863 is the most common copper nickel to find rotated, and you'll often find those on the bay too. In higher grades, including yours, you can generally add $20 to the value. Unless they are in MS grades, then the rotation generally does not add extra money to the coin.
neat coin though! is yours copper nickel or bronze?