You can now create Amazon RDS database instances running Oracle Database on Micro instances.
This new, option will allow you to build, test, and run your low-traffic database-backed applications at a cost starting at $30 per month ($0.04 per hour) using the License Included option. If you have a more intensive application, the micro instance enables you to get hands on experience with Amazon RDS before you scale up to a larger instance size. You can purchase Reserved Instances in order to further lower your effectively hourly rate.
These instances are available now in all AWS Regions. You can learn more about using Amazon RDS for managing Oracle database instances by attending this webinar.