Personally I use crashplan, its more expensive than your max price requirement if you use their cloud services, but I also back up way more data (300+GB), mostl

Personally I use crashplan, its more expensive than your max price requirement if you use their cloud services, but I also back up way more data (300+GB), mostly family photos+videos. Also, since its unlimited storage I don't really care if I suddenly have a couple of extra gigs to store after xmas or whatever. Oh and finally I can use the same app to backup to my home server so basically everything is backed up locally and remotely with one app and is encrypted/deduplicated. I used to use Arq and it worked great but then the backups became too big. EDIT: forgot you wanted opensource... oh well... anyway this works for me.