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.
eBay sellers that have tons of sales and specialize. You can learn to read between the lines and see that decom goods are what they do.
SaveMyServer is a perfect example. Don’t know if they sell drives though.