[_delirium]

Getting an idea of a collection's total value would be interesting. But where would the valuation estimates of individual works come from, to add up? Predicting the likely sale price of a given work of art seems like a pretty difficult prediction problem. The primary data source would probably be past sale prices of similar items, but "similar" has quite a bit of complexity to it, and there isn't even a good public dataset of past sale prices. Most collector-to-collector sales are private, and galleries/dealers are secretive about their own data. As far as I can tell, auctioneers like Sotheby's come up with estimated price ranges for works coming up for sale through fairly labor-intensive, case-by-case research that draws on non-public information about past prices and current market interest (and even their price estimates are frequently way off).