Override Woo Product Price

/*
 * make all products price to zero
 */
add_filter('woocommerce_product_get_price', 'dctit_set_products_price_to_zero', 99, 2 );
add_filter('woocommerce_product_get_regular_price', 'dctit_set_products_price_to_zero', 99, 2 );
add_filter('woocommerce_product_get_sale_price', 'dctit_set_products_price_to_zero', 99, 2 );
// Variations
add_filter('woocommerce_product_variation_get_regular_price', 'dctit_set_products_price_to_zero', 99, 2 );
add_filter('woocommerce_product_variation_get_price', 'dctit_set_products_price_to_zero', 99, 2 );
add_filter('woocommerce_product_variation_get_sale_price', 'dctit_set_products_price_to_zero', 99, 2 );
function dctit_set_products_price_to_zero ( $price, $product ) {
    //remove cached prices
    //wc_delete_product_transients( $product->get_id() );

    $price = 0;
    return $price;
}

//variable products
add_filter('woocommerce_variation_prices_price', 'dctit_set_variable_products_price_to_zero', 99, 3 );
add_filter('woocommerce_variation_prices_regular_price', 'dctit_set_variable_products_price_to_zero', 99, 3 );
add_filter('woocommerce_variation_prices_sale_price', 'dctit_set_variable_products_price_to_zero', 99, 3 );
function dctit_set_variable_products_price_to_zero ( $price, $variation, $product ) {
    //remove cached prices
    //wc_delete_product_transients( $product->get_id() );

    $price = 0;
    return $price;
}