The cost computation can be arbitrarily complex; it's not a matter of just echoing the values you fill in on the admin page.
If you're worried that customers will be astonished by your pricing structure, you can change the anchor text to make it more obvious that it's a priced service.
define('GIFT_WRAP_EXPLAIN_LINK', 'Gift Wrapping Pricing');
Or you can alter your template to just show a text message saying this is a priced service; final pricing will be provided on the next page.
If it's appropriate for your cart, you can certainly modify your template to echo the admin page settings, but this is not a general solution.