It should cost a little less than $30 per day if you accept the default
instance sizes when you're deploying. The year-long free tier on AWS
probably doesn't apply because it limits you to a couple of very small
instances. Once you submit the deployment it takes a bit less than an hour
to be ready, and the tutorial may take you a couple of hours or less.

If you want to save your progress but take a break (e.g. overnight), you
can stop the instances and restart them, however they'll come back with
different IP addresses, so you'll need to look up the new IP address to log
into as the links in your email will have the original address. More
details are in the docs:

http://www.cloudera.com/content/www/en-us/get-started/cloudera-live/aws-documentation.html

If cost is a concern, you may prefer the QuickStart VM. It includes an
almost identical tutorial, but it runs on your workstation instead of the
cloud.

Hope that helps!