Step Functions Express Workflows. Express Workflows orchestrate AWS services at a higher throughput of up to 100,000 state transitions per second. It also provides a lower cost of $1.00 per million invocations versus $25 per million for Standard Workflows.

(10 transitions x 100,000 executions + 1 retry x (100,000 x 10% executions)) x $0.025 per 1,000 state transitions = $25.25

Keep in mind that the AWS Step Functions charges come in addition to any data transfer charges and to the cost of any AWS services you use within the workflows. For example, if these 100,000 workflow executions result in $600/month AWS Lambda charges plus $100/month in the data transfer charges, the total cost would be:

$600 AWS Lambda charges + $100 data transfer charges + $25.25 Step Functions charges = $725.25 per month for the entire system.

https://www.serverless.com/guides/aws-step-functions