I read a ticket saying that you don't want to support other S3 compatible providers than Amazon. You were saying that they were not compatible with Amazon and it would mean a lot of work to adapt each of them. I don't agree: Synology does it with their backup solution for NAS drives: You can choose S3 compatible storage, enter the API url and it just works, we backup 1.3 TB of data using it. I think that should be possible for Akeeba Backup Pro as well.
There are other reasons than pricing for not using Amazon: Bad support, privacy issues, unethical behaviour like tax evasion or abuse of market power. Amazon is a no-go for a lot of users and it would be easy to implement for example aruba.it. Since there are some libraries for S3 servers on linux there is an increasing number of providers offering S3 in their own datacenter.