Cool! If you are looking at shared filesystems on EC2, you might also want to take a look at ObjectiveFS[1]. Works in all regions and on GCS, and you can mount your filesystem securely (end-to-end encryption) between regions.
But I also can't afford S3's bandwidth pricing.. I could, however afford to run an S3-API compatible service myself with bandwidth pricing I could afford.
But then you wouldn't let me use it because then I'd be "enterprise".