If you want to upgrade the "internal storage" the drive needs to be formatted by the shield and can not be used by anything else. It also limits this drive to 128GB, even if it holds more it only partitions off that quantity. For this storage a solid state flash drive is ideal. I use this Corsair. If you want to store your actual media as "external storage" there is no limit. I run my entire Plex server and use multiple WD Elements from 8-14TBs. I also have a few WD passports that are great because they don't take an external power source. To run multiple external hard drives directly from the shield I use a powered usb 3.0 hub. When I first started the journey I bricked 3 seagates in a month. I haven't had any issue with any of my WDs.
Currently as of 8/5/2021 1:45 AM CDT the price for WD 14TB Elements is $271.22.
My last order of these was Sep 29, 2020 at $259.99.
https://www.amazon.com/gp/product/B07YD3G568
Best Buy's current equiv. drive, 14TB WD Easystore, is currently $319.99.
14TB = 12.7 TiB
I took this drive, shucked it, and mounted it at /media/large with an ext4 file system.
At $271 = $19.35/TB as of posting this comment and still dropping for external elements 14TB WD.
https://www.amazon.com/gp/product/B07YD3G568/ref=ox_sc_act_title_1?smid=ATVPDKIKX0DER&psc=1
I have a guess that as it slowly trickles down, the more hungry ones are going to buy sooner because they fear missing out. Will it go back up again? Don't know but it's something to watch for sure.
One of the drives I am currently using that works perfectly is this one. I haven't had any issues at all.
It appears to be a "daily deal" in the U.S. for $200 (yeah, yeah, $199.99 for the foolish): https://www.amazon.com/14TB-Elements-Desktop-Drive-WDBWLG0140HBK-NESN/dp/B07YD3G568
It's 250 but they do come down to 200 a few times a year