My favorite billing mistake was forgetting to delete an unused elastic IP address and then realizing I was being charged $34 / month for 2 months just to have i

My favorite billing mistake was forgetting to delete an unused elastic IP address and then realizing I was being charged $34 / month for 2 months just to have it exist while doing nothing. Edit: It's exactly $33.62 and I was mistaken on what caused it. It came from having a NAT Gateway just idling which is $0.045 per hour x 747 hours = $33.62 on us-east-1. I know it's not the biggest mistake ever, but these things creep up on you when you use CloudFormation and it continuously fails to delete resources so you're left having to manually trace through a bunch of resources. It's easy to leave things hanging.