I’ve found a website that currently have the TP9 Elite SC mags in stock.
Note that they’re 10-round mags, though, but you can easily alter those mags to accept 12 rounds. They have the pink extension base plate.
I just ordered two of them. I’ve also checked the reputation of the website. They’re legit.
UPDATE (11/15/2021): I’ve a tracking number and they should ship either today or tomorrow!
UPDATE (11/18/2021): Wow! They’ve arrived! 2 days ahead of schedule!