Setup a billing alarm for your AWS account with cloudformation

template.yaml

AWSTemplateFormatVersion: "2010-09-09"
Description: Billing Alerts for your AWS Account

Parameters:
  Email:
    Type: String
    Default: youremail@somerandomdomain.com
    Description: The email address to receive alerts per email
  Phone:
    Type: String
    Default: "+3212312828345"
    Description: The mobile phone number to receive SMS message alerts

Mappings:
  EstimatedCharges:
    AlarmRange:
      "Threshold": 10 # Triggers an alarm if charges go above $10

Resources:
  BillingAlert:
    Type: AWS::CloudWatch::Alarm
    Properties:
      AlarmActions:
        - !Ref BillingAlertTopic
      AlarmDescription:
        !Join [
          "",
          [Alert for $, !FindInMap [EstimatedCharges, AlarmRange, Threshold]],
        ]
      ComparisonOperator: GreaterThanThreshold
      Dimensions:
        - Name: Currency
          Value: USD
      EvaluationPeriods: 1
      MetricName: EstimatedCharges
      Namespace: AWS/Billing
      Period: 21600
      TreatMissingData: ignore
      Statistic: Maximum
      Threshold: !FindInMap [EstimatedCharges, AlarmRange, One]

  BillingAlertTopic:
    Type: AWS::SNS::Topic

  AlarmSubscriberEmail:
    Type: AWS::SNS::Subscription
    Properties:
      Endpoint: !Ref Email
      Protocol: email
      TopicArn: !Ref BillingAlertTopic

  AlarmSubscriberSMS:
    Type: AWS::SNS::Subscription
    Properties:
      Endpoint: !Ref Phone
      Protocol: sms
      TopicArn: !Ref BillingAlertTopic

Deploy using the following command:

 aws cloudformation deploy --template template.yaml --stack-name billing-alerts --capabilities CAPABILITY_IAM --region us-east-1 --parameter-overrides Email=YOUR_EMAIL Phone=YOUR_PHONE_NUMBER

Based on: https://github.com/tarasowski/aws-billing-alarm-cloudformation-template. Extended by: https://github.com/Nxtra/aws-billing-alarms