On average, I think auction prices fall somewhere in between wholesale and retail though there is a lot of gray area where each one of these values begins and where one ends. I remember watching an episode of antiques roadshow a while back and the one of the appraisers was explaining the different types of value estimates one can give. In roughly increasing order, they are wholesale, auction, retail, and insurance.
To me the order makes a lot of sense. Someone insuring a collectible is going to want to be confident the value estimate in the event of a loss will be enough to cover the replacement cost which typically means insuring for more than retail. From the perspective of the dealers, they will tend to avoid auctions if lots go for more than what they are willing to pay too often. From the perspective of the collectors, they will shun auctions if items keep on selling for more than what they would have to pay elsewhere. The dealer's maximum willingness to pay is around wholesale while the collector's maximum willingness to pay is around retail or the price charged by a dealer. If auction prices stray too fall below wholesale, it will attract lots of bidders thus increasing prices whereas if it too far above retail, it will discourage potential bidders and prices will fall. Auction prices will gravitate towards somewhere between wholesale and retail.