They seem pretty similar to the values from pcpartpicker. (https://pcpartpicker.com/trends/price/memory/)

Probably not tracking eBay but retail stores..

Pcpartpicker has no plot for the 16GB DDR5 category (2x8GB?), which is the one value that makes absolutely no sense in the ramtrack plots.

But if you look at individual DDR-2x8GB items on pcpartpicker, it becomes obvious that ramtrack is just completely off here (why would 16GB be only 6% cheaper than 32GB, that is just not credible).