this is the easiest approach
<TextBox Text="{Binding Value, StringFormat='$#,##0.0000;$(#,##0.0000)'}" />
the value is your double or decimal money, but you said it was "not attached to anything." I donβt see how this is possible, but you can do it by code if you want to.
value.ToString("$#,##0.0000;$(#,##0.0000)");
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