The problem with Elastic IP, from my understanding, was that I often need to spin up say a dozen instances for a short period of time, but otherwise don't need

The problem with Elastic IP, from my understanding, was that I often need to spin up say a dozen instances for a short period of time, but otherwise don't need the IPs, so it seemed it would end up costing to have those all available but only temporarily in use...though adding up the cost, it'd only be $45 a month (12 * 0.005 * 24 * 30) so perhaps that's not a big deal.