Comment by JeffeFawkes

I picked up a handful of "580gb" microSD cards off AliExpress recently, with the goal of using them in mp3 players around the house. I figured they'd be reject 64gb sdcards, and I was right - they averaged 50-58gb of usable storage. Perfect for writing once, reading many times, and cheaper than even 16gb legit cards. They can be useful, just know they may also die at any moment.