Some folks might have missed that memory prices on the whole are up [1] 90% since Q4. The memory used by the Pi 5 is up 700% [2]! Raspberry Pi are working the issue by releasing new memory variants that are cheaper[2]. Edit: You can still walk into a Microcenter and get Pi 5 16GB for US $289! 1. https://au.pcpartpicker.com/trends/price/memory/ 2. https://www.raspberrypi.com/news/a-new-3gb-raspberry-pi-4-fo...
An 8 GiB DIMM for a desktop or server is using 8x 1 GiB chips or 16x 512 MiB chips (9/18 for ECC). An 8 GiB Pi uses a single 8 GiB chip. That's the same density as you would use for 128 GiB or larger sticks.