Hi @rowi1de ,
Welcome to Sonar Community 
Yes, self-hosted k8s/Helm deployment of SonarQube is free to use. However, only Community Edition is free to use in the sense that you can scan projects and view their results. The non-Community editions (Developer Edition, Enterprise Edition, Data Center Edition) of SonarQube cost money (see Download | SonarQube for the differences between editions). The deployment method is independent of the cost of SonarQube.
You should use our official Helm chart, not Bitnami: sonarqube 4.0.2+325 · sonarsource/sonarqube. GitHub source of our SonarQube helm charts here: helm-chart-sonarqube/charts at master · SonarSource/helm-chart-sonarqube · GitHub
Notice in the readme that you can change the edition. Look for image.tag in the Helm chart.