I answered this in another thread, There is no easy answer. Normally, the amount paid is the declared value. Apparently the seller declared the appraised value, so the paperwork would reflect that, and maybe that was used. Customs has the right assign another value to any shipment, you haven't told us if they did that.
The seller should have used the invoice price as declared value, but it is rather late for that unless you want to launch an appeal to Customs. Seller may have provided the appraised value for insurance purposes, to protect both you and him against loss or damage.
No one can help you if you don't provide enough information. If you don't want to make that info public on the boards, go and consult a Customs Broker and be prepared to pay the consult fee.
