AWS CloudWatch Metrics Pricing with Different Resolutions

Hi, yes you pay the same price for the metric itself in all 3 cases above, so a metric sent once every hour would cost USD 0.3 for one month, and you don't have to pay an extra if you send the metrics every 10 seconds, it will be charged the same.

The part of your bill that will vary if you send metrics every 10 seconds vs every minute is the API: you will pay for more API calls. API calls are charged USD 0.01 per 1,000 requests after the free tier (see https://aws.amazon.com/cloudwatch/pricing/).