This pricing is actually not that far-fetched. Consider that the competitor UptimeRobot offer 50 monitors at 5 minutes interval for free. You can lease servers

This pricing is actually not that far-fetched. Consider that the competitor UptimeRobot offer 50 monitors at 5 minutes interval for free. You can lease servers very cheaply nowadays, uptime monitoring is not resource-intensive and is an easily distributed workload. The most expensive part of the operation is likely to store the monitor results in a database.