Why YSK: Online platforms, particularly some very prominent offenders, may artificially spike prices before creating "discounts". Whether this is intentional or the result of third party sellers fighting amongst themselves, I cannot say. Either way, don't blindly purchase something because of a deal (camelcamelcamel is great to see price history if you just care about Amazon). Besides, if your sole motivation to purchase something is based on a discount, you might be better off cutting consumption instead.
Source: I run fetchnotifs. While checking the logs this morning, I was scared to death I deployed a bug to production—Nope, it's just that day of the year.