Is there any way of getting the saved EC2 instance image and running it on virtualbox on my personal computer?
The official way is only if it was originally imported into EC2
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ExportingEC2Instances.html
If you have previously imported an instance into Amazon EC2, you can use the command line tools to export that instance to Citrix Xen, Microsoft Hyper-V, or VMware vSphere. Exporting an instance can be useful when you want to deploy a copy of your EC2 instance in your on-site virtualization environment.
You cannot export an instance unless it was previously imported into AWS