WooCommerce Add Price On Application

// Change empty (not zeroed) prices to "Price on application"
add_filter('woocommerce_empty_price_html', 'noprice_callout');

function noprice_callout() {
    if ( is_product() ) {
        // return a link ONLY when viewing the product page
        return '<a href="contactus.php">Contact Us for the price</a>';
    } else {
        // otherwise return some standard text
        return 'Price on application';
    }
}