woocommerce/loop/price.php

price.php

<?php
// Display lowest price of variant on product archives WooCommerce
// Format "Starting at %s per unit" - Exp: Starting at $4.5 per unit
// Put this file to folder /woocommerce/loop/ of your theme

if ( ! defined( 'ABSPATH' ) ) {
	exit; // Exit if accessed directly
}

global $product;

$price_html = $product->get_price_html();

if ( $product->get_type() == 'variable' ) {

	$min_price = $product->get_variation_price( 'min', true );
	$price_html = sprintf(__('Starting at %s per unit'), wc_price( $min_price ));
	
}

if ( !empty( $price_html ) ) : ?>
	<span class="price"><?php echo $price_html; ?></span>
<?php endif; ?>