Are we talking about a "sweet spot" in terms of price-to-performance? If so, then the current sweet-spot for DDR5 is that most people should probably go with DDR4 instead.
The performance benefits of DDR5 are almost nonexistent for gaming at this time, and lower-end kits actually tend to perform worse in games than DDR4 due to their increased latency. While there's some potential for higher-clocked kits with tight timings to increase performance slightly over DDR4 in certain games, the difference is so minor that it's arguably not worth pursuing unless the rest of the system is already utilizing top-end hardware. For most modern games, you would get way more performance by putting the money toward graphics hardware instead, or even toward a better processor in CPU-limited titles. So unless we're talking about a gaming system that's going to be fitted with at least an RTX 3080 level graphics card and a 12700K level CPU, DDR5 is probably not even worth considering, as that money would likely be better spent elsewhere.
There was a benchmark leak suggesting that "maybe" the upcoming Raptor Lake processors might potentially benefit more from DDR5 in certain workloads, but those results seemed questionable, and not necessarily related to games. Supposedly, the Raptor Lake K-series processors should be launching within the next few months, so we'll likely know more then. And of course, if you happen to wait until then before building a system, it's possible that DDR5 prices might have trended further downward by that point, though I wouldn't expect any huge changes on that front.
As it currently stands, it's possible to get a 32GB kit of DDR4-3600 CAS16 for around half the price of a kit of DDR5-6000 CAS36, or close to a $150 difference. And as far as gaming performance goes, even when running modern titles on an RTX 3080 at a lower resolution like 1080p, you would be hard-pressed to perceive any performance difference between the two, with both memory types typically performing within a couple percent of one another. There are some memory-intensive application workloads where DDR5 can perform notably better, like with file compression, but for the most part application performance tends to be relatively similar too, at least not enough to justify a $150 price difference. So from a value-perspective, there currently is no sweet-spot for DDR5.