94 
Display “FREE” if WooCommerce Product Price is zero or empty
In older versions of WooCommerce free prices used to display as “FREE!” and products with empty prices were not publishable/purchasable. Now they’ve changed this around, but I still believe “FREE” looks much better than “$0.00”. It’s much more enticing, isn’t it?
Well, here’s how you restore the old WooCommerce functionality – as usual it’s as simple as using a PHP filter provided by WooCommerce and overriding the default behavior.
PHP Snippet: Display “FREE” if WooCommerce Product Price is Zero
/**
* @snippet Display FREE if Price Zero or Empty - WooCommerce Single Product
* @how-to Get tutoraspire.com FREE
* @author Tutor Aspire
* @testedwith WooCommerce 5
* @donate $9 https://www.tutoraspire.com
*/
add_filter( 'woocommerce_get_price_html', 'tutoraspire_price_free_zero', 9999, 2 );
function tutoraspire_price_free_zero( $price, $product ) {
if ( $product->is_type( 'variable' ) ) {
$prices = $product->get_variation_prices( true );
$min_price = current( $prices['price'] );
if ( 0 == $min_price ) {
$max_price = end( $prices['price'] );
$min_reg_price = current( $prices['regular_price'] );
$max_reg_price = end( $prices['regular_price'] );
if ( $min_price !== $max_price ) {
$price = wc_format_price_range( 'FREE', $max_price );
$price .= $product->get_price_suffix();
} elseif ( $product->is_on_sale() && $min_reg_price === $max_reg_price ) {
$price = wc_format_sale_price( wc_price( $max_reg_price ), 'FREE' );
$price .= $product->get_price_suffix();
} else {
$price = 'FREE';
}
}
} elseif ( 0 == $product->get_price() ) {
$price = 'FREE';
}
return $price;
}