Seagate has introduced the Exos M series, a range of enterprise-grade mechanical hard drives available in 30TB and 32TB capacities. The two models, the 30TB CMR ST30000NM004K and the 32TB SMR ST32000NM003K, each offer a minimum of 3TB per disk and use a standard 3.
Not programming skills, but sysadmin skills.
Buy a used server on EBay (companies often sell their old servers for cheap when they upgrade). Buy a bunch of HDDs. Install Linux and set up the HDDs in a ZFS pool.
Or install TruNAS and chill.
I went with Linux and BTRFS because I just need a mirror. Lots of options and even more guides.