There is no way to know exactly how many people have an 1893-S Morgan Dollar. 116 years ago the US Mint in San Francisco struck 100,000 of the 1893-S dollars so, we can say there are no more than 100,000 people with one of these coins.
AU means almost uncirculated which is a grade for the coin, depending on the grade on the coin and the year of it, the value of the coin can be from $25 for the most common and lowest grade dollars all the way to $575,000 for the second highest grade, most rare silver dollar(1893S)(no proof 70 silver dollar has ever been found)
This is the key-date coin of the series, a circulated example has values of $2,000.00 to $40,000.00 depending on grade. a uncirculated coin is valued at $75,000.00 to more than one million also depending on grade.
In my opinion they are the Liberty Seated Dollars: 1870cc, 1870s, 1872cc, 1872s, 1873cc, 1873s the Morgan Dollars: 1879cc, 1884s, 1889cc, 1892s, 1893s, 1895, 1897o, 1901, 1903s, 1904s the Peace Dollars: 1934s. All coins listed have values over $1,000.00 in the grade of MS-63. Dollar coins dated from 1971 to 2000 have no silver and most only have face value.
1892 Morgan silver dollar1892, no mint mark, very fine condition-$15.00, uncirculated-$275.00, proof-$1,600.00 1892, CC mint mark, very fine condition-$65.00, uncirculated-$775.001892, O mint mark, very fine condition-$15.00, uncirculated-$225.001892, S mint mark, very fine condition-$40.00, uncirculated-$45,000.00