Amazon S3 is a static file hosting service from Amazon. Storage costs $0.15 USD per Gb and data transfer (outgoing) costs $0.18 USD per GB up to 10TB. As an online backup solution, it would cost less than $20 / month to store 100Gb, assuming you’re not uploading / downloading more than 20% every month.
That’s pretty cheap by backup standards. But for commercial static file hosting, it’s insanely cheap. Particularly given the fact that it will scale from a few GBs today, to several TBs tomorrow.
I currently spend $5.40 / month for 3Gb of online backup with rsync.net. I might consider switching to Amazon S3, although probably not for my daily backups because I get unlimited bandwidth on rsync.net and top notch support. For image archiving on the other hand, it looks very tempting.
The best thing, there’s no minimum spend. You don’t have to commit to spend hundreds of dollars to benefit from enterprise class storage.