[nijave]

You can do that with native CloudWatch monitoring, too, but it doesnt work well with spikey charges like up front reservations and things billed at the beginning of the month

Technically they are "anomalies" but there's no human interaction required so you get false positive alarms. It also doesn't work well beyond a certain $ amount since the error bars get pretty big

Is DataDog better with that?

[mullingitover]

With DD you can set up monitor downtimes in advance of expected anomalies. Also, at the beginning of the month costs can drop suddenly, so what you can do is set up separate 'over' and 'under' threshold monitors, and then set up downtime on the 'under' threshold at the beginning of the month.