Ron Guth: The 1800 "AMERICAI" variety features a die flaw that mimics the letter "I" immediately following the word AMERICA on the reverse. The flaw is not an actual letter "I", which would have been the engraver's error; rather, it is simply a flaw that looks like an I, in perhaps the most fortuitous position possible. This is considered a major variety in the Bust Dollar series, as it is visible to the naked eye. Two varieties (BB-191 and BB-192) comprise the entirety of this variety. As expected, both varieties share the AMERICAI reverse, but were struck from different obverses.
The PCGS Condition Census for this major variety features coins ranging in condition from AU-55 to MS-63, thus collectors have several high-grade options from which to choose. The finest examples certified by PCGS (as of March 2012) are a pair of MS-63s.
"Colonel" E.H.R. Green Collection - Partnership of Eric P. Newman & B.G. Johnson (St. Louis Stamp & Coin Co.) - Eric P. Newman, who paid $50 - Eric P. Newman Numismatic Education Society - Heritage 11/2013:33510, $223,250
Amon G. Carter, Jr. Family Collection - Stack's 1/1984:228, $9,900