What you actually need is a provider that will guarantee the durability of your data even if they (temporarily) cut off your access to it for lack of payment[1]. Anything else is just a level of indirection that suffers the same problems.
---
[1] I don't actually know if anyone does this, let alone AWS. Here's a quote from Tarsnap's FAQ—where you'd think cperciva is someone who would have considered the "I had no idea my infrastructure was relying on this service until it shut off" use-case:
> You will be sent an email when your account balance falls below 7 days worth of storage costs warning you that you should probably add more money to your account soon. If your account balance falls below zero, you will lose access to Tarsnap, an email will be sent to inform you of this, and a 7 day countdown will start; if your account balance is still below zero after 7 days, it may be deleted (along with any data you have stored) at our discretion. (If you can't add money yet but will be able to later, contact us and explain the situation. We're reasonable people and simply knowing that you're alive and haven't forgotten that you were using Tarsnap is very helpful.)
7 days is probably reasonable in the case where there's an active IT staff who will notice when, say, servers stop backing up. But if nobody's watching for that...
