Reducing you observability because of costs is very unlucky. I was really disappointed by ApplInsights costs and started looking for an alternative immediately.

In my case with my requirements having a Loki with Grafana was enough, but my projects and the company are small.

P.S. I suspect AppInsights is very expensive because of its obsolete tech, I guess it uses a relational database which is very questionable desicion for logs and metrics.