As the questions implies I want to add a setup-fee for certain products. The additional fee should be displayed in the product mask, cart and checkout. How is it possible to get that functionality?
I found a solution using this plugin. It's very easy. If you want to display the setup fee in your product description, use the following code:
$id = get_the_ID(); $fee_name = get_post_meta( $id, 'product-fee-name', true ); $fee_amount = get_post_meta( $id, 'product-fee-amount', true ); echo $fee_name . ' - ' . $fee_amount;