These tools tend to be very expensive in my experience unless you are running your own monitoring cloud. Either you end up sampling traces at low rates to save on costs, or your observability bill is more than your infrastructure bill.

We self host Grafana Tempo and whilst the cost isn’t negligible (at 50k spans per second), the money saved in developer time when debugging an error, compared to having to sift through and connect logs, is easily an order of magnitude higher.

Doing stuff like turning on tracing for clients that saw errors in the last 2 minutes, or for requests that were retried should only gather a small portion of your data. Maybe you can include other sessions/requests at random if you want to have a baseline to compare against.

I've tried HyperDX and SigNoz, they seem easy to self-host and decent enough