How Much does CloudWatch Logs Cost
So CloudWatch logs are not free, but there's no up-front cost and the price is cheap to get started. Here are few things you can pay attention for the CloudWatch logs.
Free tier 5GB Data
Lots of AWS Service will automatically be sending logs to CloudWatch logs, for example, Lambda function, ECS, or CodeBuild. You can, of course, turn off the logs depending on the service. 5GB should be a good amount of free tier if you start as an individual.
Paid Account is cheap
For paid account, or after the free tier, you'll charge $0.03 per GB for storage. If you store 100GB of logs, will cost you $3 per month. It also charges when collecting data, or analyze the data, both are $0.5 per GB and $0.03 per GB.
Delivery to S3 is Cheaper
Seems like if you store the logs to S3 might be cheaper base on the AWS' documentation, for instance, if you store the VPC flow logs to CloudWatch logs will cost you $0.50 per GB, but if you choose to deliver to S3, then will cost you $0.25 per GB.
Cleanup the un-used CloudWatch logs
To check the CloudWatch logs, first, you go to CloudWatch at AWS, then click the logs section then you'll see all the Log Groups, sometime you might have some un-used logs, AWS services already deleted but logs are still there, you might want to clean it up once a while, seems like by default all logs' retention is never expired at default.
CloudWatch logs are cheap to get started, don't forget data ingest and analyze the logs will cause you money, also remember to delete some unused to save money.