1k xmr rear diff

Okay fella’s…I have 66 hours on my machine and the rear diff went out. I had changed the fluid twice so I was hoping to avoid this issue but it happened so now I need to fix.
Where is the best place to buy the rear diff for my machine. I have seen them from 750-1200 bucks.
Is there a better replacement so I don’t have to do this all over again in the future?