were can I buy the back glass replacement

So I work at a cell phone repair place, we do almost everything but mostly phones

1. so i do know that most repair shops could get you one but most places dont stock them.
2. You could also try amazon, but the repair process can be tricky if you do not have the proper tools so thats why id reccomend taking it to a repair shop,
3. you could also try to find a vendor who sells them, i believe mobile defenders sells them but im not sure if they sell them to indivudals. if you do find a vendor or amazon that can sell you one here is the guide Samsung Galaxy Note9 Back Cover Replacement
4. if you have any other questiuons please fill free to ask me