Lots. Roughly US$112.50 per month. CrashPlan and SpiderOak are better price value, although I might look at using this to have a secondary backup of critical items. Even that, for me, though, is about 200GB (photos & music) or about $30/mo.

I'm a bit biased, but I don't feel S3 is the best possible fit for a frugal consumer's backup data. S3 is a high performance, general purpose solution capable of very low latency.

Having that performance makes it more expensive than an archival specific solution, which tolerates latency just fine as long as high throughput is maintained.

There's a reason why Mozy, Carbonite, SpiderOak, etc. all run our own data centers. I can sell a 100GB account for usable across unlimited computers for $50 per year and be profitable.

That said, the market certainly has plenty of room for more backup choices, and any option to help people avoid data loss is a win. An exclusively Mac app seems like a good idea.

I don't know how other people do it, but certainly for me, I have things that are at different levels of importance to me. And a lot of the most important are not really all that big, nor are they changing particularly frequently. I wouldn't pay a premium of $100 a month just for the convenience of having everything backed up in this super-redundant, universally-accessible way.

I would happily use a product like Arq (or Time Machine) for my documents and current photos, to make sure the backup is always current, and then whenever the backup hits 50gb, move it over to an off-site drive (at work, a relative's house, even in a safety deposit box).

You can't figure out what 750 * 0.15 comes to?