Let's compare cloud vs on-premises costs for data storage. Note that all major cloud providers also charge for ingress/egress and API calls when reading or writing data.
This pricing calculator provides an estimate of on-premises costs, as well as cloud provider costs. Your actual bill will depend on a number of factors, including exact server component prices at the time of purchase, data center selection, or cloud region.
Storage, TB:
Percent of Data Downloaded, per month: