Keep in mind also that the used market is a completely different animal than the new market. For example:
- many used models are no longer available new (or in short supply)
- many new versions of previous models are of inferior quality to the original
- some used guns are one-of-a-kind and can't be sourced new
- used guns are always "in stock"
- new models are seldom "rare" and, even if they are, the price is predetermined, not based entirely on demand
- unfortunately, too many used firearm sellers think what they paid for a piece and any improvements they made are relevant to the resale value. They are not. A new buyer only cares about what he gets for his/her money. What the seller paid or overpaid is irrelevant.
- sellers of used guns often have an emotional attachment to the gun being sold (in such cases, the gun should be retained and not sold). New gun sellers want to sell guns, they seldom get attached to them (and should buy them personally if they do).
- used guns can have "provenance". This is to say, they can have been used by famous or important historical figures, or they can be a model that was historically significant. New guns are just an object. To collectors, the provenance can sometimes account for more of the value than the piece itself. Imagine the value of the ordinary service rifle that was used by Lee Harvey Oswald!
I could go on, but the point is that the used market involves many more factors than the new market and the two can't always be compared straight across. There are also many who don't recognise all of the above factors and simply have a mistaken impression of why other pieces that are for sale are worth more than theirs. Those folks may price their items too high simply because they have an inflated impression of the used market overall, based on not knowing the reasons for the valuations.
And, always remember, you have to judge each firearm on it's own merits. Not every Holland and Holland is worth what is being asked for it and not every Baikal is worth only $300. Precious few makers use only one grade of steel. Many times the steel used in a particular gun is stamped on the barrels, precisely because it can vary. Individual guns may receive far more attention to fit and finish detail, including inlays and engraving. Regardless of how the gun started out, it's current condition is what controls the market price.
The ability to judge the value of a used gun requires intimate knowledge, not only of current models and values, but of the previous generations as well. It requires also the ability to accurately judge the condition of a piece, knowledge of repair and/or refinishing costs, and availability of ammunition and reloading supplies.
I suspect some of the instances of high prices in the EE are exactly as you suspect - over priced. Many others, though, are simply a case of the potential buyer not knowing the true value of the item. And, don't forget, different items have different values to different people based solely on their individual preferences.
My own bias is heavily in favor of used. For my money, there is seldom anything a new gun can do that a vintage gun can't do better - not because quality new guns aren't currently being produced for every purpose, but because energy and labour costs being what they are these days, the cost of producing equivalent guns today is high. And, therefore, the prices of modern
quality firearms are extremely high. Used guns of the same high quality are available, if you have the knowledge and the patience needed to find them. They are relatively cheaper only because of their reduced value as used and the additional risk inherent in buying used.