As unfortunate as that is this is not a universal problem, where I live 14/16/18/20 are readily available and competetive in price/TB, and they have been for a few years (at least the 14/16TB ones, not sure about 18/20). One would hope that the roll out of larger capacity drives would also result in more availability in your region - perhaps not of the largest capacity that exists, but at least of a larger capacity than is currently available to you.
Lucky you! I want to build a nice RAID array (currently my storage setup is ad hoc supporting about 14 TB), but I don't see why I should use 12 TB as a base when higher is available (outside my region).
How are SMR drives used in data centers? I was under the impression that they are not great for any type of raid setup, which I'd imagine would be typical.
Also without any increase in speed, rebuild times will probably become more of a problem, right?