you are right S3 is highly cost but it is very reliable and secured , finally it depends on your budgetErr, we are talking terabytes here ...
Where I live, S3 Standard costs me 2,45 Cent per Gigabyte per month ... I currently have (only) 6 TB of video data, which would sum up to 1764 Bucks per year ... no thanks!
And that does not even include the fee of 9 cent per GB, if I transfer more than 100GB per month (outgoing) so if I needed a restore of all my data, that would be around 500 Bucks