I checked spot instances just now, and it was less than $0.10 an hour. So for batch jobs that might be an option. And if you're using it interactively, than you

I checked spot instances just now, and it was less than $0.10 an hour. So for batch jobs that might be an option. And if you're using it interactively, than you can always go EBS backed and just turn it off when you're done.