I think it's more a reflection of the way in which the 3 week online bidding process was managed by the top 3 or 4 bidders.
It was such a race early on for prospective buyers to outbid each other, that by the time the 'real' bidding started in the last day or so, the top 2 bidders were paying the penalty for the earlier price action. That's the reality of this type of auction I guess.
Adding the purchase price, buyers premium (7.7%), GST brings the figure to a tad under $800,000.
There are other, higher spec and newer aircraft available at prices not much more than this.