Question from someone who has zero knowledge about managing infrastructure: is all of that absolutely necessary? Only one is marked "we can afford to lose", but $228/mo for a monitoring server seems extremely excessive. Even $44 for "private communcations" (I'm assuming something like RocketChat) surely have cheaper alternatives?
We're self-hosting most of our infra on bare-metal, on the best price/quality hosting provider I know of (OVH). I doubt you could store ~1TB of metrics going back 4 or 5 years on fast NVMe storage for less than this in the cloud.