Woops: Brainfade. Yes, 1.5 cents/instance/hour, not 10x that. Still, quite expensive I think.
With Amazon CloudWatch... at a rate of $0.015 per hour for each Amazon EC2 instance you choose to monitor...
As an example, a developer may want to monitor 10 Amazon EC2 instances 24×7 for a 30-day period. The Amazon CloudWatch cost would be $108 (or $0.015 per Amazon EC2 instance hour x 10 Amazon EC2 instances x 24 hours per day x 30 days)...
That is close to what it costs to run a single instance to collect all your statistics (75$ if its small + your time is worth something!).
That is close to what it costs to run a single instance to collect all your statistics
Assuming you need a completely separate instance which couldn't do anything else but monitoring, which is unlikely to be the case.
[source : http://aws.amazon.com/cloudwatch/]