Are you using a shipping cart or just paypal buttons? I set my website up using wordpress with the woocommerce plugin. All the product prices and shipping fees are done on my end. I don't have to set anything in paypal.
At the moment just using the PayPal buttons which link to my friend's PayPal account's payment page. I would love to integrate a shopping cart, though there is still so much stuff to do that will have to wait.
Does anybody else have experience with this and could offer some advice?