Adding parameters to text

Not 100% sure your end goal but you’re using woocommerce so you can maybe start with:

<?php
global $post;
$args = array(
    'include' => array( $post->ID ),
);
$products = wc_get_products( $args );
//print_r($products); /* see them all */

$product = wc_get_products($post->ID);

foreach ($product as $item_id => $item ) {
	$item_data = $item->get_data();
	echo $item_data['name'].'<br>';
	echo $item_data['regular_price'].'<br>';
	echo $item_data['sale_price'].'<br>';
}	
?>

if you put that in your footer.php it will display the woocommerce meta data for that current product. I don;t know how you have your three prices saved so you can always uncoomment the line //print_r($products); and see the full array to find the keys you need.

The answer depends on how they are “pulling” values. Using PHP prior to output is very different than using JavaScript or similar client side script.

I’m guessing they are using something like JavaScript. In that case you could wrap the value they want in a <span> element and provide a unique id attribute the script can use to find the element in the DOM. Something like this:
€<span id="prijzen-ex-1-4">37,95</span> Excl btw

You can actually include custom data attributes like “data-prijzen” in HTML elements that script can directly access. But you still need a unique ID and such a custom attribute makes manual document maintenance more difficult because now any price change must be managed in two different places. It makes more sense when everything is managed automatically by code.