This is a snippet from developers.google.com

Iowa (us-central1) Los Angeles (us-west2) Oregon (us-west1) Northern Virginia (us-east4) South Carolina (us-east1) Montréal (northamerica-northeast1) São Paulo (southamerica-east1) Belgium (europe-west1) Finland (europe-north1) Frankfurt (europe-west3) London (europe-west2) Netherlands (europe-west4) Zürich (europe-west6) Mumbai (asia-south1) Singapore (asia-southeast1) Sydney (australia-southeast1) Hong Kong (asia-east2) Taiwan (asia-east1) Tokyo (asia-northeast1) Osaka (asia-northeast2)
Component Billed Price (USD)
Per tunnel (per hour).
For 99.99% availability for HA VPN, you must configure two tunnels; four tunnels if working with an AWS peer gateway.
IPsec traffic Charged as if the traffic were regular egress traffic. If the Cloud VPN tunnel connects to a gateway in GCP, egress pricing to the region containing that gateway applies. See General network pricing.
If the Cloud VPN tunnel connects to a gateway outside of GCP, Internet egress rates apply.
Public IP for VPN gateway Charged according to IP address pricing.

Google does not charge for forwarding rules that send traffic to the VPN gateway.

If you pay in a currency other than USD, the prices listed in your currency on Cloud Platform SKUs apply.