If it's XIV related, there's really no question that can't go in the RIT.
I found my copy on Amazon for 16 new but I guess that's back when it was held in even less regard. If you can, get a used one, just make sure you contact the seller and make sure the key isn't tied to an SE account. Not like you need the disc for any reason as you can just DL the client, what you're paying for is the product key. If that's been used, it's worthless.
XI Wiki



