[swarmee]

I think you're fooling yourself if you think that the majority of big bidders know about all the auctionhouses and when the last days are. Sure, many do, but many whales are still only on eBay or Christies or REA. They are loyal just like cigarette smokers. They buy stuff in their spare time. So the wide variance in prices paid makes sense, because the level of information also varies widely.
Also, some auctionhouses just don't describe their items well, and some do. However, I would think a smarter way of doing this is buying dealers lots in big auctions, and then parting them out on COMC to Amazon and eBay for the lower grade/commoner cards, and then doing the grading thing with the really nice ones.