Just to throw one other thought into the mix (and I am not saying the OP was involved in this). In the same way as sellers sometimes get a friend to bid, in the hope of running the price up, then drop out if they overcook it and run the risk of actually winning the item themselves, buyers can run a similar dodge to get the item really cheap.
It works by letting a couple of people put in the traditional, low, early bids, then the two working in conjunction get into a "bidding war" before the price gets too high. They place several bids, leapfrogging each other, and run the price up way above what is sensible. This then means that the auction continues, possibly for a few days, with no further bidders because the price is too high and puts the competition off. Then just as the auction is about to end, one pulls out which removes all their bids and the other guys bid tumbles all the way back down to where they started.
So, a lens that may be worth 200.00 is quickly run up to say 25.00 by other bidders just marking the auction to come back to later. The two guys working together then rapidly bid it up to 300.00 which stops any further bidding. The high bidder then drops out just as the auction is about to end, and the other guy is left as the winning bidder at around 27.00 or so.
Such price drops can sometimes happen, even if the two high bidders are not collaborating. A bidding war can run the price up, then one bidder wins another auction for the same item, so no longer needs this one and cancels their bid. No collusion and no malice intended, but it has stopped people bidding who would have bid otherwise, had the "current bid" been showing at the eventual (reduced) winning amount.
In either scenario, the seller has not got a fair price for his item because of somebody cancelling a bid. If that happens, I can understand them not wanting to go ahead because the auction has (IMO) been a 'misauction' due to what happened. In the opening post, we are told the seller cancelled because the lens reached a price way below it's value.
In such cases, I feel the fairest thing is to simply relist the item straight away and let everybody bid again. That is what happens in a land based auction room, if there is a problem with the bidding process they simply start again.
I don't know if that is the case here, but maybe the seller has some justification, if the last minute bid cancellation caused the high bid to drop significantly.