Problem using DISTINCTCOUNT with multiple filters

I would like to calculate the distinct count of values in a column on a filtered list to use in a formula.

I’ve read the other posts on this, but am still stumped.

I have a larger dataset that I have narrowed down to 14 rows/purchases by using  filters from 3 distinct fields (Amount, Item Description, and Purchase Date).

The table shows the 14 remaining transactions, but there are only 12 distinct individuals who made those purchases (Homer and Milhouse each have 2 purchases; everyone else, just 1).

I want to multiply the distinct number of people on the filtered list by a constant: 100. I am looking to return 100 for every one of the 12 distinct people listed in the filtered table. In this case, the total I want is 1,200.

I’ve tried a couple different ways.  The first is simple and assumes the filters are applied to the PBIX file itself:

Est Value Simple =
100 * CALCULATE ( DISTINCTCOUNT ( 'Springfield Purchases'[ID] ) )

I also tried with the filters in the formula itself:

Est Value w Filters =
100
    * CALCULATE (
        CALCULATE (
            DISTINCTCOUNT ( 'Springfield Purchases'[ID] ),
            FILTER ( 'Springfield Purchases', 'Springfield Purchases'[Amount] < 500 ),
            FILTER (
                'Springfield Purchases',
                'Springfield Purchases'[Item Description] <> "Unknown"
            ),
            FILTER (
                'Springfield Purchases',
                'Springfield Purchases'[Purchase Date] >= DATE ( 2016, 1, 1 )
            )
        )
    )

Both of them return the same value: 1400 instead of the 1200 I’m looking for.