I do my best to keep the sales data updated, but there are many that may be missed or private sales I would not know about. I check eBay primarily and Abebooks when I can.
If you were the seller or buyer for any proofs, and you’d like to contribute toward keeping the sales data as complete as possible, then please submit the form below whenever you bought or sold a proof and I will add it to the list. It’s completely anonymous. Thanks!