Debug.WriteLine(value.ToString("$#,#.000"))

The following example displays positive values as currency values, negative values in parentheses, and zero as the string Zero.

    Debug.WriteLine(value.ToString("$#,#.#;($#,#.#);Zero"))

This example program lets you enter values and enter or pick format strings to see the results. When you change the value or format string, the ShowValue routine displays the result. It simply converts the value into a Double and passes its ToString method the format string.

Private Sub ShowValue()
    Try
        Dim value As Double = Double.Parse(txtValue.Text)
        txtResult.Text = value.ToString(cboFormat.Text)
    Catch ex As Exception
        txtResult.Text = ""
    End Try
End Sub