New? Google Shopping feature
https://lifehacker.com/how-to-get-google-to-let-you-know-when-the-price-drops-1838810254
I've been running a plugin that does this on Amazon (Keepa). It inserts a historical price chart onto pretty much every product page and will e-mail you when it drops to your desired price. Very handy and makes total sense that Google would do it, too.
I could not find it on desktop.