In the UK I was looking at DDR4-3200 SODIMM last week for some mini-pcs... and decided to pass after looking at the price graphs. It's spiked in the last few weeks.
camelcamelcamel is the best for amazon items - choose a stick, look at the graph.
There is a bit of annoyance as items come in and out of stock (ie. out of stock often means inaccurate price); so its often better to find a product on amazon and look here.
