Strangely, they seems to have a blue screen fx-82ES! But if you do buy one, you will get one with light green screen. (At least I never see one) I guess it might be some kind of prototype that CASIO once produced but didn’t made it into the market (or just very briefly).
But the screen itself is not that mysterious, it is just a simple negative mode STN LCD, and we can mod our 82ES’ screen to negative mode ourself. All we need to do is peel the old front polarizer off, and paste new one in a different angle.
I used a original fx-82ES to mod:
Peel the original polarizer off: Note this is not reversible! Think twice before you do.
Paste the new one. You can crop it from a larger polarizer.
And here we go!