Offisite Backup

I am trying to find the best and most “economic” way to setup an offsite backup. I have a client that does not want to spend money on it so I am exhausting all of my options before I tell her the bad news. She has about 50GB of data that needs to backup at least once a day to an offsite machine located in her house.

Please let me know if you have any opinions or advice on this. Anything at this point would be helpful.

Thank you in advance folks!