With that huge of a range, wouldn’t it be better to either figure out which of the two is an outlier or leave it outdated? The high end is over double the low end. Downvoted this one anyway.

Do you know what the buyout was on the 2900 sale?

I see the burning Noh was linked here as comparable case, but there's a fairly substantial difference between the two situations:

The noh had no other sales; its last sale was well over 2 years before the first of the used sales there occurred. On this one, the second-most recent sale was only a little over 4 months before - not that much longer than our regular window within which we evaluate sales. It should be noted that there, it took about two years to sell for the listed amount, which would advocate 6000 being an outlier. I am aware that this does not fully hold as within the two years it took, the halloween market has changed significantly.

The time that took to sell aside - it shows that in the recent past, a third data point would support 2900 much more than 6000. It's why I'd be interested to know if this was listed, and if so at how much, before it sold at 2900. If it was listed at less than 6000 it makes for hard evidence that 6000 is too high here.

Another noteworthy difference between this and the noh case is that on the noh, the low end sale was already a substantial raise over its previous value. This in particular is often something that tips the scales in favor of updating with a ridiculous range as opposed to leaving outdated - the more desperate the times, the more desperate the measures. In this case, the low end sale is on par with its current value - in fact the noh's low end sale was further off its previous value than this has ever fluctuated ever since it was priced in keys. This means that there is less incentive to resort to something crazy, like we did on the noh.

The things above considered make me much more convinced that leaving this outdated is a better choice than repricing this with this range. As an alternative when you wish to update this now, I would be more inclined to go with 2900 flat based on the above evaluation than I would be to get the full range. I will stress here once more that the burning Noh should be seen as highly exceptional, and should not be used as a de facto template for how to deal with discrepant sales. I have tried to emphasize the differences here as much as I could in order to clarify that.

I would see either of the aforementioned two options as better than this range here.