I will assume that the OP has local backup under control. If not, I'd highly recommend getting a either a couple of $100 external hard drives and backing up THERE first. Secondly, under the "there's no such thing as too many backups" theory, I'd spring for a Blueray drive and burn 25 GB or 50 GB Blueray disks.
To answer the question asked, Apple's iCloud is free for 5 Gb, and costs $0.99 per month for 50 GB. The OP does not hint at his devices, but at the same time, I'm not sure iCloud isn't available for anyone. I have Apple devices, so perhaps the price is only for Apple owners, I wouldn't know.
https://www.apple.com/icloud/