You might ping Ernest Durbin @ the PSF to see if they can help out. The PSF already has substantial cloud infrastructure and relationships with the big vendors (e.g. I think PyPI gets free storage in S3), so they might be able to set up another storage bucket pretty easily.
The problem is that we would need to automate the clean-up of old build artifacts. On Rackspace, the https://github.com/ogrisel/wheelhouse-uploader tool I developed would do that automatically (for nightly-builds) but honestly. I used Apache Libcloud so it might work almost out of the box with AWS S3 blob storage but I have never tested and honestly I am not interested in maintaining that tool if more standard alternatives based on twine can do handle retention logic automatically without custom development. Also, managing AWS upload credentials for a bunch of loosely coupled open source projects will be a mess (it was for the rackspace based solution, Matthew Brett was a SPOF with only myself as a high latency backup spare). I would rather have each project be autonomous in their ability to share and revoke upload credentials among maintainers. -- Olivier