Violas are sized by arm length so double check with her instructor first. It is alot of money - I'd talk to her and see how she feels. When you buy a good instrument, you know that, assuming its decently taken care of, you can recoup at least a decent portion of what you've spent. If she uses it for a few years and then stops and you can sell if for 50% of what you spent, thats not too bad.
Another way to go would be to wait till June when there will be more used instruments available. Rental returns, people who bought and now are done with instruments etc. Pretty sure Shar has used or "blem" instruments from time to time.
dd1 10/05
dd2 11/09
and ... a mini poodle!