You can save anywhere from 60-91% using a spot instance. The downside is, the instance can be preempted anytime.
Create a spot instance.
gcloud beta compute instances create spot-example \ --provisioning-model=SPOT \ --instance-termination-action=STOP \ --image-project=ubuntu-os-cloud \ --image-family=ubuntu-2004-lts \ --machine-type=e2-micro \ --project=your-project-id \ --zone=us-central1-a |
Delete instance.
gcloud compute instances delete spot-example \ --project=your-project-id \ --zone=us-central1-a |