<ListBox ItemStringFormat="{}{0:C}" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:sys="clr-namespace:System;assembly=mscorlib">
  <sys:Int32>-9</sys:Int32>
  <sys:Int32>9</sys:Int32>
  <sys:Int32>1234</sys:Int32>
  <sys:Int32>1234567</sys:Int32>
</ListBox>