Currency formatting on ComboBox items

<Window.Resources>
    <my:CurrencyConverter x:Key="currencyConverter" />

    <DataTemplate x:Key="thingTemplate" DataType="{x:Type my:Thing}">
        <TextBlock
            Text="{Binding Amount,Converter={StaticResource currencyConverter}}" />
    </DataTemplate>
</Window.Resources>

<ComboBox
    ItemSource="... some list of Thing instances ..."
    ItemTemplate="{StaticResource thingTemplate}" />

<ComboBox ItemStringFormat="c">

<TextBox Text="{Binding Path=Value, StringFormat=Amount: {0:C}}"/>