SxSs are old technology. Fully developed, 100-150 years ago depending on how you look at them. So there are few, if any, new modern features beyond recent screw-in chokes, which on a SxS I hate. So there is no modern, hip interest. Two triggers do take a bit of getting use to. It took me about thirty seconds to figure them out and remember to shift my finger. The two trigger excuse, is just an excuse to me, for anyone who can pump a gun can move a finger back and forth. There have been countless times I have seen a semi gun shot dry, while the SxS get the last shot off, to anchor a bird. Fast does not always end up being an advantage.
Value is subjective and is part of demand or perceived demand. If you think something is going to sell fast, sell for top dollar and you think you want it, you will be more willing to pay a higher price. Conversely, if you think something will be difficult to sell, is very common, or easy to find another example, perhaps better or cheaper, you will have little incentive to buy it at all, except under almost giving it away conditions.
Other than guns and muscle cars you see this the most in antiques, a very soft market. What 30 years ago was a hot item, is a total dog these days, in most cases. I settled an estate, with a house full of antiques, fine china, silver and silverware, which 30 years ago would have brought more than the house but which I struggled to find takers within the family for free and selling it was a long and very unsatisfying process. I had many oriental rugs with little demand until I found a dealer who had sold most of the rugs 40-50 years ago, or he and his father had, and he found out I had one very oversized rug he wanted. It was almost 20' X 40' and he said he had not seen one like it for sale in ten plus years. He bought that rug and all the rest for more money that all the rest of the household brought. That rug was really made up of many smaller rugs, perfectly matched and joined together I was told. I went from struggling to get a buyer to a dealer who cut me a check for the low six figures. Right buyer, right item still will bring a dollar. Oriental rugs are not quite a dime a dozen, but they are not rare anymore like when I was a kid.
It is buyer market on the low end guns or antiques, but higher grades or rarer ones will still command a good price. Low grade, common ones have little, a shooters interest, at best, but higher graded ones will still have interest or demand. But even then, there are limits like London double which could be built bought new at $100,000+, that when sold used, will struggle to bring a third of that price.
