Between inflation generally, and DDR4 being obsolete and unsupported by current desktop or server CPUs, it would be unsurprising for DDR4-3200 DIMMs to be at an all-time high even without the current DRAM price shock. You can never count on old memory types dropping to bargain prices, because the major manufacturers are always eager to migrate the bulk of their production capacity to current-generation memory.
That process usually takes years.
Here the price hike was pretty instant as secondary effect of DDR5 evasion in two waves. I July and now in October.
There is usually no shortage of old working PC components as they also are avalable used and tested from people decommissioning and upgrading systems. These are not some rare parts in normal market situations.
I made a habit of maxing out motherboards a year or two before upgrading to an new platform. This was always dirt cheap until like 5 years ago.
Yeah the cheapest time to buy old tech is always just when the new stuff has come out. That's when suppliers are trying to shift old stock at cheaper margins.
You can take a look at the 5800X3D and how it was at its cheapest about 2 years ago when AMD was winding down production and Zen 4 had been launched.