Ron Guth:
This is the only overdate among the Draped Bust Quarter Dollars and, as such, it is very popular with collectors. The overdate is clearly visible to the naked eye, even on worn specimens. Despite its popularity, the 1806/5 Quarter commands only a small premium over the regular type.
Approximately two dozen Mint State 1806/5 Quarters have survived, most often in MS62 to MS64. The PCGS CoinFacts Condition Census starts at MS63 and tops out at MS66 with the remarkable T. James Clarke/Knoxville Collection/D. Brent Pogue example.