Reading this, I can only conclude that the US market is quite a bit more dystopian than what I see in Europe.
For both RTX 50* and RX 9070 series (and the Intel Battlemage) I see no issues with retail availability: all variants are available from stock with several vendors to choose from for each, even RTX 5090 is €2900, including all taxes and tariffs.
I bought a B580 (€300), an RX 9070XT (€900) and an RTX 5070 (€700) over the last few weeks with slightly inflated prices, which is why I just returned the most egregious variant, an RX 9070XT sold at €900 for a full refund today.
It currently sells at €789 (always including taxes) and I preferred to keep the RTX 5070 selling at €649 today, just a tad above EU MSRP of €619. I could still return for another week and buy it again at €50 less, but I don't get minimum wage for my time.
Including the 40* series in any comparison today makes no sense, those cards haven't been produced in months, are quite simply no longer available as new and thus quoted prices are just trailing noise ripples.
eBay may be a social phenomenon or a refuge for the totally desperate, but when retail availability is not an issue, new goods are best bought from e-commerce or retail.
And I am truly shocked that price/feature portals such as geizhals.eu don't seem to be available in the US: evidently you keep hordes of journalists busy digging up "facts" where we can just query an excellent and up-to-date database in all comfort.
I guess some of our social code isn't all that bad.