Show different strings for stock level of 0, 1, and many items

ithemes-exchange-inventory.php

<?php
$inventory = it_exchange( 'product', 'inventory', 'return=true' );

if ( 0 == $inventory ) {
	echo 'Too Late!'; // We're completely out
} elseif ( 1 == $inventory ) {
	echo 'There can be only one!'; // There is one in stock
} else {
	printf( 'We have %s in stock.', number_format( $inventory, 0, null, ',' ) );
}