At work and in my personal projects I use a Prometheus + Grafana setup and it's very easy to set up. Not sure what you mean with the complex and setup costs for a Grafana stack?

Alerting with the Prometheus AlertManager is also pretty straight forward and I'm looking at dashboards every day to see if everything is running smoothly or tracking down what's not working well if there are any issues. Grafana dashboards are always the second thing I look at after an alert fires somewhere and it has been invaluable.