Note that AWS offers archival storage for $1/TB-month and Google has promised $1.23/TB-month later this year. These prices are competitive with raw storage, so the alternative is to go without backup.
"S3 Glacier Deep Archive
This new storage class for Amazon Simple Storage Service (S3) is designed for long-term data archival and is the lowest cost storage from any cloud provider. Priced from just $0.00099/GB-mo (less than one-tenth of one cent, or $1.01 per TB-mo), the cost is comparable to tape archival services. Data can be retrieved in 12 hours or less, and there will also be a bulk retrieval option that will allow you to inexpensively retrieve even petabytes of data within 48 hours."
https://aws.amazon.com/about-aws/whats-new/2019/03/S3-glacie...