It was to be expected that the Ryzen 7 3700X and Ryzen 9 3900X would be in high demand; the former is $70 cheaper than the 3800X for about the same performance, and the latter is the world's first mainstream 12-core CPU that also happens to be AMD's best gaming CPU (though not by a massive margin). What is unexpected is the ongoing shortage with the 3700X and 3900X that has not entirely gone away since July 7th. These new CPUs have only been available in small quantities since launch and have been selling out almost immediately, leading to price gouging on eBay.
The shortage is so bad that third parties are selling the 3700X and 3900X at inflated prices. The 3700X is being sold for almost as much as a Ryzen 7 3800X at retailers like Amazon and eBay while the 3900X has been going for as much as $750 (the MSRP of next month's Ryzen 9 3950X which has 16 cores) on Amazon, with most sellers on Amazon and eBay pricing it around $600. Today, you can find 3700Xs at most retailers, but on Amazon they are only up for preorder and will only arrive at the end of August at the earliest.
Other Ryzen SKUs, however, seem to have escaped these supply issues, most notably the 3800X, which is basically the same as the 3700X but binned a little better and $70 more. Perhaps AMD has intentionally constrained the supply of the 3700X to encourage impatient people to just buy the 3800X. On the other hand, the Ryzen 5 3600 doesn't seem to have ever gone out of stock (which would force buyers to choose the 3600X), so perhaps AMD's supply issues are entirely down to unprecedented demand.
Sadly, there doesn't really seem to be an obvious solution for AMD or buyers other than just waiting or buying what's available right now (whether it's at MSRP or not). It's not easy for AMD to just increase production on these CPUs, which have a unique supply chain and require a 12nm IO chiplet from GlobalFoundries and one or two 7nm core chiplets from TSMC. AMD also uses the 7nm core chiplets for its EPYC Rome data center processors that offer up to 64 cores, which could be a factor as the company ramps up its data center lineup.
There's also the matter of the 3900X and 3950X requiring two compute chiplets, unlike the 3800X and below which require just one. Unfortunately, it remains unclear when we will see widespread availability of the Ryzen 7 3700X and Ryzen 9 3900X.
