Yes. I should include this info in the README calcs. For my usecase I intend to do 4 - 10 PUTs per hour, since they are batched. 10 PUTS/h = 7300 PUTs/month = $0.073/month. The key here is infrequent
Be most careful with retries. Saw a case where the bucket wasn't writable and the code just retried in a loop. You get charged for the API call, successful or not.