A small number of Congress Bicentennial Silver Dollars are known with the reverse die rotated 180 degrees from normal (so-called medal turn).
Anthony Swiatek estimates that there are probably 40 to 50 in existence (as of 2009). He has owned a total of seven of these rare variants in the past twenty years. Sale prices range from $1,000 for a coin with problems to $4,500 for a super quality example.
PCGS is not responsible for the accuracy or authenticity of Ebay listings.