The code that controls the display of the price on the product results page is near lines 469-475:
php:
<?php
if($row_MaxMinPrice["MinPrice"] > 0) {
echo number_format($row_MaxMinPrice["MinPrice"],2);
} else {
echo number_format($row_WADAProducts["ProductPrice"],2);
}
?>
You would need to add in an if statement here to check if this $row_WADAProducts["ProductPrice"] value was equal to 0, if so display your alternative message, else display the ProductPrice. This is a custom update that will require you to edit the php code.
