Auction results can be searched at price guide http://www.antiquecast.com Sotheby’s is now included. The Antiquecast super search lists sale items at major auction sites. Pictures are often available. Although this site is pitched towards antiques and collectables anything auctioned can be searched. Concise searches are best with the 3 most characteristic terms. Worth a bookmark for ready reference.

or e-bay!

You may be right with respect to this particular type of item, but eBay is not the only auction around, nor does it authenticate items.