personal offsite backup

I just read a newspaper article about house fires, and it struck me that one of the things that might well be lost in such a mishap would be my financial records etc that are stored on my computer. All carefully backed up to a local disk :) So I need to consider an offsite backup. What do people use and/or recommend? My initial thinking is to install some sort of disk and computer (pi?) in a nephew's house and install some automatic backup software. So I'm open to suggested implementation ideas or alternative ideas. I'd like to avoid solutions that involve subscriptions. TIA, Dave