You should be able to build your own. AWS does allow servers to be configured in a n-tier environment. You put the application servers (mid-tiers) in one security group and the database server in the other security group. You can then do the RAPID INSTALL just like any other hosts.
The only thing is that the pre-built E-Business Suite image (AMI) is not ready yet from Oracle. But it should be easy to build it ourselves.