Booking the ticket for her is defeintely better than transferring the miles.

As to how much? That is a question.

Your cost to accumulate does not matter. It would be a negotiated point somwhere between what you could get for them, and what the ticket would cost her.

Looking at the numbers, I would go with .01 per mile ($750 - $900). That is the floor for just "burning" miles, and still gives her a discount over the published fare.

In theory you should get a bit more, but it is not a great redemption to begin with, and friendship does come into play here.