Definitely a market, however I still can't use remote backups because they're too expensive.

My backup repository (I use SVN) is 100gb, mostly from photos. At current market rates that's something like $30/month+ AFAIK, so instead I just make hardcopy backups and store them offsite. If I could get 200gb for $10/month I'd sign up, that's still a few years away though.

And erm, I don't think you can "one way encrypt" something for a backup service, you need to be able to decrypt it (thus making it non-one way).

You'll need to promote why your service is better than say Google Drive or Dropbox.