Then you've answered your own question really, there isn't much information on UNC grades for the ones you're looking for.
Personally I wouldn't disregard prices over 2 years old for items that seldom come to market, they at least will give you an idea of the market. Also, as a bidder, when I make a purchase through an auction house I make my bid taking commission into account as I think a lot of others do, I don't think removing the commission price is giving you a true figure IMO. Especially so in the case of rarer items that receive much higher bids than your run-of-the-mill coins.