...New Stamps are the less wanted, from what I know the bronze alloy is different
New stamps are still desirable and use the same bronze alloy as the older models as far as I know. I personally have read nothing to the contrary.
I've had Old and New Stamp alloy tested by top labs and there isn't a difference. It's just B20. There are construction differences, particularly in the bells, as the factory changed from sledge in bells to pressed in. The style of hammering also changed. But the alloy shows continuity.
I presume "less wanted" is standing in for "sell for lower prices". The lower prices for New Stamps vs Old Stamps has been documented, but there is more to it than just "wanted". Price is an equilibrium between supply and demand, if you believe basic economics. Plus there are other factors in prices which I've documented including an interaction between weight and price and production era and diameter.
The new stamps and the new new stamps were the last of the Old K's made in Istanbul. I have another 20 inch old K new stamp which is one of the most musical cymbals I own. On the A side I have a trans stamp from around 1950 that is to die for, and looks as good as it sounds. But, we digress from the topic at hand.
Actually, the topic fits very well as far as I'm concerned because it highlights several of the issues which relate to why vintage gear gets higher prices. That in turn might inform us about what "modern gear" might be the future collectable gear.
The example of Robert Spizzichino cymbals is a good one in that regard. His cymbals are now selling in the same price range as Old Stamp K Zildjian Istanbul cymbals. So the combination of fine craftsmanship and limited availability is what one might look for in current drum gear. Craviotto springs to mind.
Many of the things drummers post about vintage prices and "the vintage market" turn out to be beliefs which aren't based in actual data. Here's a data based review from the perspective of vintage electric guitars. This is germane because it isn't uncommon for drummers to say the same things about the vintage market, and for drummers to use the vintage guitar market (and the "huge increases") to support their beliefs about the vintage drum (and cymbal) market.
https://reverb.com/news/are-used-gear-prices-going-up
Note that "old growth wood" or "50 year old wood" in vintage drums may be like "different alloy" in vintage cymbals and guitars. It may or may not have a detectable sonic effect. But what matters to price is what people believe about it. That's more about advertising than science. My take on it as a researcher on cymbal prices is:
Nothing but an Old K is an Old K. Some cymbals other than Old Ks can enjoy the same Old K price advantage, but the sound and look has to be right, and buyers need to believe prices are going up.
Nothing but "50 year old wood" is "50 year old wood". Some modern drums can enjoy the same vintage price advantage, but the sound and look has to be right, and buyers need to believe prices are going up.