Best you can do is take great pics, good descriptions, and be a trusted seller of luxury goods. Beyond that, absolutely zilch can be done in a general auction - the outcome is reliant on the bidders, or rather, what bidders.
On another weekend, two bigwigs duke it out and the price goes beyond $2K, on a bad weekend, the bidding war is the battle of bottom feeders and you end up selling the item for a song.
Way it goes. Law of averages suggests in long term a good estimate and final value will be correlated. However, in a single auction one could not expect to hit this law of average with high probability (this would typically be quite a low probability less than 5 in 10). One has to look at a variance and items could go well above or well below estimate.