You can view your Invoices in the SiteBuilder control panel. Here you will be able to see all issued invoices, you can view each invoice in more detail by clicking View next to the specific invoice you wish to look at.
Please note that the total value of an invoice does not necessarily mean that is the full amount you have paid. SiteBuilder offer discounts from time to time, if you received a discount the invoice will be paid by a credit (for the value of the discount) and your payment.