Did you consider using a mirror network, with servers run by external organizations, instead of going with AWS bandwidth for rubygems? Seems like that would be a good approach for the static/bulk part of your dataset, and there are lots of companies and universities who are set up to serve software. (The mirror I manage serves about 50 TB/month for several Linux distros, and many sites are larger.) Do the work and infrastructure required to manage these networks make them not worthwhile?
Edit: Found a post [0] calling for a rubygems mirror network. Otherwise there is lots of information about setting up local mirrors of the repository.
Edit: Found a post [0] calling for a rubygems mirror network. Otherwise there is lots of information about setting up local mirrors of the repository.
[0] http://binarymentalist.com/post/1314642927/proposal-we-have-...