This is a just a side note, if you’re privileged to have an old AWS account prior to EC2-VPC, then you’ll need to ensure that you create a correct default VPC. Unfortunately if you fail to have a valid VPC, Juju will try and get an instance-type for that region and because there is no valid VPC, you’ll end up with a d2.xlarge instance. This instance isn’t cheap!
You can fix this by either creating a new AWS account, or creating a correct default VPC, one that correctly picks up when creating the new instances.