When I published Lambda that is called regularly like a cron task someone asked me how much would it cost (a fair question taking into account you pay per use, not per infrastructure). With lambda you pay for two things: a request/invocation and the time times memory used.
For that particular case (1 request per minute) the monthly cost would be:
|60 requests/hour * 24 hours/day * 31 days/month|
|0.1 seconds minimum charge per execution * 44640 requests * 0.128GB of memory|