A CloudWatch alarm on a billing metric could also be used to send you SMS, email, hell even call you if you want to wire a webhook up to a quick and dirty twilio app (via SNS)
In fact, we use an SNS->Slack gateway running on a free Heroku dyno to get out alerts in a Slack channel (which is pushed to phones/etc), along with other CloudWatch alarms related to performance.
Honestly, this issue of "I don't have any visibility into what I'm spending" is a waste of energy. You do, and you can have AWS bug you as intensely as you want with updates as frequent and as urgent as you need
In fact, we use an SNS->Slack gateway running on a free Heroku dyno to get out alerts in a Slack channel (which is pushed to phones/etc), along with other CloudWatch alarms related to performance.
Honestly, this issue of "I don't have any visibility into what I'm spending" is a waste of energy. You do, and you can have AWS bug you as intensely as you want with updates as frequent and as urgent as you need