Currently, there is no charge for using AI Platform Vizier. However, your studies are limited to 1,000 trials and you do pay for any Google Cloud resources you use with AI Platform Vizier. For example:
AI Platform Training and AI Platform Prediction: When you use AI Platform Training or AI Platform Prediction, you incur AI Platform Training costs or AI Platform Prediction costs.
Cloud Storage: You may incur costs for Cloud Storage resources. These costs vary by API.
Pricing calculator
You can use the Google Cloud pricing calculator to create an estimate of your monthly charges.