You can buy an appliance from Cloudian and have you S3 on-premise and support. They're basically 100% S3-compatible. I don't know the details of their pricing

You can buy an appliance from Cloudian and have you S3 on-premise and support. They're basically 100% S3-compatible. I don't know the details of their pricing, but they're production grade in the reald sense of the word. I am not affiliated with them in any way, but I interviewed with them a couple of years ago and left with a good impression.