The Lens Price Database, Lens$db, has prices and physical specifications for over 400 lenses, including: all Canon EF prime lenses and EF Extenders; all Canon EF L-series zoom lenses, plus a few others; a large selection of “alternative” manual focus lenses from Carl Zeiss, Leica, Nikon, Olympus, Pentax, Voigtlander, and other brands; a variety of lenses from Sigma, Tamron and Tokina; and, a selection of Medium Format Mamiya 645 lenses that are more-or-less compatible with EOS cameras, and with the Mirex Tilt-Shift adapter. The prices are mostly for used equipment in excellent to mint condition, based on eBay sales and list prices at many camera stores.
I have been meaning to ask you how this all started. Was this an outgrowth of the CELOSDB database you compiled when you switched from Pentax to Canon?