private function getProductPrice(ProductInterface $product)
    {
        $price    = 0;
        $document = $this->getDocumentSource($product);

        if (isset($document['price'])) {
            foreach ($document['price'] as $currentPrice) {
                if ((int) $price['customer_group_id'] === GroupInterface::NOT_LOGGED_IN_ID) {
                    $price = (float) $currentPrice['price'];
                }
            }
        }

        return $price;
    }