I've been using Crashplan for my extended family as well, you get 10 machines with unlimited storage for something like $120 per year. Linux client has been working great, I'd definitely recommend them.
My plan had expired. And i ended up not renewing(since i was cutting down on all 3rd party services that i use). So i just moved to an external hard disk and "Back in Time" on linux.
But i've been looking at re-subscribing to it again.
You might want to check it out. https://www.crashplan.com/en-us/features/
Also it was one of the few services that had a client that worked on Linux