[vidarh]

S3 alone is expensive enough that it often pays to rent managed servers or instances elsewhere to act as a frontend cache for any external access to the files if you for whatever reason "must" use S3 (durability would be a good justification - getting that right is hard; getting it to the point where you trust it to be right is even harder)

E.g. 1TB worth of retrievals from S3 can buy me a dedicated server with 16TB of disk space and 30TB of inclusive traffic. Doesn't take a very big cache hit ratio before caching all external reads becomes profitable.

If cost is a consideration, it's pretty rare for AWS to be the way to go for anything but batch processing where you need instances or short periods of time in the first place.