Ron Guth:
The relatively large mintage for the 1868-S Quarter Dollar belies its true rarity. In low grades, this date can be found rather inexpensively, but once the grade reaches Extremely Fine, the price begins to soar. In Mint State, this date is very scarce and valuable. A direct comparison with the lower-mintage 1868-P illustrates two principles: 1) collectors had difficulty obtaining coins from San Francisco, or 2) they were satisfied enough with the coins they obtained from Philadelphia. In 1868, collecting by date and mintmark combinations was virtually unknown, so there was little demand for coins from the branch mints. However, at least one collector saved an original example, as the PCGS Population Report shows a single MS67. This coin has not yet appeared at public auction, so we have no clear indication of what it might be worth, but it would be substantial.