<h1><?php the_title(); ?></h1>

<h1><?php the_title(); ?>
    <span>
    <?php
        if (promo-price exists) {
            // 1. Code to get promo price from DB

            // 2. Code to display text
            $price_details = sprintf(' - %s with promo code: %s', $promo_price, $promo_code);
            echo $price_details;
        }
    ?>
    </span>
</h1>