
The estimates published in the auction catalogues are more likely to be based on the vendor's reserve price (low estimate being often one bid above the reserve) then to be based on the wisdom and experience of the auctioneer.
It is not uncommon for wines to go unsold, because the vendor is often resolved (initially, at least) to recover his original outlay and storage costs.
Sometimes, however, the vendor gets lucky because someone hasn't done their homework and assumes that a buy at low estimate has got to be a good deal..
I'm not going to publish my database of prices, not least because I am constantly updating it, but if anyone wants to check what they should bid or find out what their surplus stock is likely to realise, then feel free to PM me.
Tom