Подправил немного - готовый вариант вот:
/**
* This code should be added to functions.php of your theme
**/
add_filter('woocommerce_variable_price_html', 'custom_variation_price', 10, 2);
function custom_variation_price( $price, $product ) {
$price = '';
if ( !$product->min_variation_price ||...