get_post_meta() get the lowest regular price from all variations

I would like to find the lowest regular price of all variations. For this I have written the following code:

add_action( 'woocommerce_before_add_to_cart_form', 'preis_von' );
function preis_von() {
    global $product;
    global $post;
    $theproductid = array(15174, 15175);
    $product_id = method_exists( $product, 'get_id' ) ? $product->get_id() : $product->id;
    if(in_array($product_id, $theproductid)) {
        $prices = min(get_post_meta( $post->ID, '_regular_price', true ));
        //rsort($prices); // sort in descending order
        //$minPrice=min($prices);
        echo '<div id="preisab" class="abpreis">Preis ab '.$prices.'€ pro Won</div>';
         ?>
        <script>
        jQuery(document).ready(function($) {
            $( ".variations_form" ).on( "woocommerce_variation_select_change", function () {
                document.getElementById("preisab").innerHTML= " ";
         });
        });
    </script>
    <?php
    }
}

But there is no output. If I use the variation ID instead of $post->ID, I get the output of the regular price for the variation. What did I do wrong?